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Chúng ta thường sử dụng console.log hoặc các hàm delay để dừng chương trình tạm thời phục vụ cho việc debug Javascript code. Những cách này khá phổ biến nhưng sẽ tốn thời gian trong việc debug.

cac cach debug javascript code tren vscode

Các cách debug Javascript code trên VSCode

&lt;!DOCTYPE html&gt;
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&lt;p id=&quot;docs-internal-guid-760886ed-7fff-c45b-c5a2-d52f590ac5e3&quot; dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;Robert Kiyosaki &amp;#244;ng l&amp;#224; t&amp;#225;c gi&amp;#7843; c&amp;#7911;a cu&amp;#7889;n s&amp;#225;ch kh&amp;#225; n&amp;#7893;i ti&amp;#7871;ng &quot;Rich dad, poor dad&quot;, &amp;#244;ng l&amp;#224; ng&amp;#432;&amp;#7901;i &amp;#273;&amp;#227; l&amp;#224;m m&amp;#236;nh thay &amp;#273;&amp;#7893;i c&amp;#225;ch t&amp;#432; duy v&amp;#7873; &amp;#273;&amp;#7891;ng ti&amp;#7873;n. D&amp;#432;&amp;#7899;i &amp;#273;&amp;#226;y l&amp;#224; nh&amp;#7919;ng c&amp;#226;u n&amp;#243;i hay c&amp;#7911;a Robert Kiyosaki m&amp;#224; m&amp;#236;nh th&amp;#7845;y hay v&amp;#224; t&amp;#226;m &amp;#273;&amp;#7855;c.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;&lt;br /&gt;1. The rich do not work for money, they make money work for them.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;2. Why would you save money when they are printing money?&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;3. &lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;&amp;#160;&amp;#160;&amp;#160;God&amp;#8217;s money: Gold and silver&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;&amp;#160;&amp;#160;&amp;#160;Government&amp;#8217;s money: Dollars, Euros, etc.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;&amp;#160;&amp;#160;&amp;#160;People&amp;#8217;s money: Bitcoin, Ethereum, etc.&amp;#160;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;4. Fake money makes the rich richer but makes the poor and middle class poorer.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;5. Assets put money in your pocket, whether you work or not, and liabilities take money from your pocket.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;6. Your house is not an asset.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;7. Rich people acquire assets. The poor and middle class acquire liabilities, but they think they are assets.&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial,sans-serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;8. The game of money is the game of mindsets.&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;&amp;#160;&lt;/p&gt;
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Robert Kiyosaki đã nói một câu rất dễ hiểu, để phân biệt đâu là tài sản và đâu là tiêu sản, câu nói đó như sau: Tài sản bỏ tiền vào túi của bạn, kể cả khi bạn có làm việc hay không, còn tiêu sản lấy tiền từ túi của bạn.

Những câu nói hay của Robert Kiyosaki

&lt;!DOCTYPE html&gt;
&lt;html&gt;
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&lt;h2 id=&quot;docs-internal-guid-78dacfad-7fff-8a54-08b4-5992593a0a18&quot; dir=&quot;ltr&quot;&gt;O(n) l&amp;#224; g&amp;#236;?&lt;/h2&gt;
&lt;p&gt;&lt;img src=&quot;../images/bai-viet/backend/big-o-do-phuc-tap-thuat-toan/bodpttt1699776872732.gif&quot; alt=&quot;&quot; width=&quot;800&quot; height=&quot;789&quot; /&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Gi&amp;#7843; s&amp;#7917; m&amp;#236;nh c&amp;#243; 1 h&amp;#224;m printElements nh&amp;#432; h&amp;#236;nh b&amp;#234;n d&amp;#432;&amp;#7899;i, h&amp;#224;m n&amp;#224;y ph&amp;#7843;i l&amp;#7863;p n l&amp;#7847;n &amp;#273;&amp;#7875; in ra c&amp;#225;c gi&amp;#225; tr&amp;#7883; i, v&amp;#7853;y &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p c&amp;#7911;a thu&amp;#7853;t to&amp;#225;n Big O c&amp;#7911;a h&amp;#224;m n&amp;#224;y s&amp;#7869; l&amp;#224; O(n)&lt;/p&gt;
&lt;p&gt;&lt;img src=&quot;../images/bai-viet/backend/big-o-do-phuc-tap-thuat-toan/bodpttt1699776905333.gif&quot; alt=&quot;&quot; width=&quot;800&quot; height=&quot;789&quot; /&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Ngo&amp;#224;i ra trong Big O c&amp;#242;n c&amp;#243; kh&amp;#225;i ni&amp;#7879;m Drop Constant, n&amp;#243; s&amp;#7869; lo&amp;#7841;i b&amp;#7887; h&amp;#7857;ng s&amp;#7889; khi t&amp;#237;nh Big O. V&amp;#237; d&amp;#7909; b&amp;#234;n d&amp;#432;&amp;#7899;i, m&amp;#236;nh c&amp;#243; 2 v&amp;#242;ng l&amp;#7863;p t&amp;#225;ch bi&amp;#7879;t nhau v&amp;#224; m&amp;#7895;i v&amp;#242;ng l&amp;#7863;p ch&amp;#7841;y n l&amp;#7847;n, nh&amp;#432; v&amp;#7853;y m&amp;#236;nh s&amp;#7869; c&amp;#243; ph&amp;#233;p c&amp;#7897;ng:&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Big O = O(n+n) = O(2n)&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#7902; &amp;#273;&amp;#226;y m&amp;#236;nh c&amp;#243; O(2n) v&amp;#224; nh&amp;#432; m&amp;#236;nh &amp;#273;&amp;#227; n&amp;#243;i &amp;#7903; tr&amp;#234;n m&amp;#236;nh c&amp;#243; quy&amp;#7873;n lo&amp;#7841;i b&amp;#7887; h&amp;#7857;ng s&amp;#7889;, v&amp;#7853;y cu&amp;#7889;i c&amp;#249;ng Big O = O(n)&lt;/p&gt;
&lt;h2 dir=&quot;ltr&quot;&gt;O(n^2) l&amp;#224; g&amp;#236;?&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#272;i v&amp;#224;o v&amp;#237; d&amp;#7909; m&amp;#7899;i, b&amp;#234;n d&amp;#432;&amp;#7899;i m&amp;#236;nh c&amp;#243; 2 v&amp;#242;ng l&amp;#7863;p l&amp;#7891;ng nhau, v&amp;#242;ng l&amp;#7863;p th&amp;#7913; nh&amp;#7845;t ch&amp;#7841;y qua n l&amp;#7847;n, m&amp;#7895;i l&amp;#7847;n v&amp;#242;ng l&amp;#7863;p th&amp;#7913; nh&amp;#7845;t ch&amp;#7841;y th&amp;#236; v&amp;#242;ng l&amp;#7863;p th&amp;#7913; hai ph&amp;#7843;i ch&amp;#7841;y th&amp;#234;m n l&amp;#7847;n n&amp;#7919;a, nh&amp;#432; v&amp;#7853;y m&amp;#236;nh s&amp;#7869; c&amp;#243; ph&amp;#233;p nh&amp;#226;n.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Big O = O(n*n) = O(n^2)&lt;/p&gt;
&lt;p&gt;&lt;img src=&quot;../images/bai-viet/backend/big-o-do-phuc-tap-thuat-toan/bodpttt1699776952503.gif&quot; alt=&quot;&quot; width=&quot;800&quot; height=&quot;789&quot; /&gt;&lt;/p&gt;
&lt;h2 dir=&quot;ltr&quot;&gt;O(n!) l&amp;#224; g&amp;#236;?&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;n! &amp;#273;&amp;#7885;c l&amp;#224; n giai th&amp;#7915;a l&amp;#224; t&amp;#237;ch c&amp;#225;c s&amp;#7889; t&amp;#7915; 1 &amp;#273;&amp;#7871;n ch&amp;#237;nh n&amp;#243;, v&amp;#237; d&amp;#7909;:&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;0! = 1&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;1! = 1&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;2! = 1 * 2 = 2&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;3! = 1 * 2 * 3 = 6&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;4! = 1 * 2 * 3 * 4 = 24&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;5! = 1 * 2 * 3 * 4 * 5 = 120&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;6! = 1 * 2 * 3 * 4 * 5 * 6 = 720&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;M&amp;#236;nh c&amp;#243; &amp;#273;o&amp;#7841;n code sau:&lt;/p&gt;
&lt;p&gt;&lt;img src=&quot;../images/bai-viet/backend/big-o-do-phuc-tap-thuat-toan/bodpttt1699777005168.gif&quot; alt=&quot;&quot; width=&quot;773&quot; height=&quot;763&quot; /&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;khi n thay &amp;#273;&amp;#7893;i th&amp;#236; s&amp;#7889; l&amp;#7847;n l&amp;#7863;p c&amp;#7911;a h&amp;#224;m &lt;strong&gt;run&lt;/strong&gt; s&amp;#7869; t&amp;#259;ng theo s&amp;#7889; n giai th&amp;#7915;a, cho n&amp;#234;n thu&amp;#7853;t to&amp;#225;n tr&amp;#234;n c&amp;#243; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p l&amp;#224; O(n!), d&amp;#7921;a v&amp;#224;o bi&amp;#7875;u &amp;#273;&amp;#7891; c&amp;#7911;a c&amp;#225;c &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p th&amp;#236; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p c&amp;#7911;a thu&amp;#7853;t to&amp;#225;n c&amp;#243; O(n!) l&amp;#224; r&amp;#7845;t t&amp;#7891;i t&amp;#7879;. M&amp;#7897;t v&amp;#237; d&amp;#7909; kh&amp;#225;c cho thu&amp;#7853;t to&amp;#225;n c&amp;#243; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p O(n!) l&amp;#224;: &lt;span style=&quot;color: #0000ff;&quot;&gt;&lt;a style=&quot;color: #0000ff;&quot; href=&quot;https://en.wikipedia.org/wiki/Travelling_salesman_problem&quot; target=&quot;_blank&quot; rel=&quot;noopener&quot;&gt;https://en.wikipedia.org/wiki/Travelling_salesman_problem&lt;/a&gt;&lt;/span&gt;&lt;/p&gt;
&lt;h2 dir=&quot;ltr&quot;&gt;O(log n) l&amp;#224; g&amp;#236;?&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#272;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p O(log n) &amp;#273;&amp;#432;&amp;#7907;c g&amp;#7885;i l&amp;#224; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p logarit. &amp;#7902; &amp;#273;&amp;#226;y m&amp;#236;nh c&amp;#243; m&amp;#7897;t v&amp;#237; d&amp;#7909; &amp;#273;&amp;#417;n gi&amp;#7843;n:&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Logarit c&amp;#417; s&amp;#7889; 2 c&amp;#7911;a 8 th&amp;#236; b&amp;#7857;ng bao nhi&amp;#234;u?&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Log&lt;sub&gt;2&lt;/sub&gt;8 = ?&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;t&amp;#432;&amp;#417;ng &amp;#273;&amp;#432;&amp;#417;ng v&amp;#7899;i 2 m&amp;#361; bao nhi&amp;#234;u &amp;#273;&amp;#7875; b&amp;#7857;ng 8&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;2&lt;sup&gt;?&lt;/sup&gt; = 8&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Ta c&amp;#243; 2 m&amp;#361; 3 s&amp;#7869; b&amp;#7857;ng 8&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;2&lt;sup&gt;3&lt;/sup&gt;=8&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Nh&amp;#432; v&amp;#7853;y s&amp;#7889; c&amp;#7847;n t&amp;#236;m &amp;#7903; &amp;#273;&amp;#226;y s&amp;#7869; l&amp;#224; 3.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#7902; v&amp;#237; d&amp;#7909; b&amp;#234;n d&amp;#432;&amp;#7899;i m&amp;#236;nh c&amp;#243; thu&amp;#7853;t to&amp;#225;n Binary Search v&amp;#7899;i input array &amp;#273;&amp;#7847;u v&amp;#224;o &amp;#273;&amp;#227; &amp;#273;&amp;#432;&amp;#7907;c s&amp;#7855;p x&amp;#7871;p theo th&amp;#7913; t&amp;#7921; t&amp;#259;ng d&amp;#7847;n, &amp;#7903; m&amp;#7895;i l&amp;#7847;n l&amp;#7863;p th&amp;#236; thu&amp;#7853;t to&amp;#225;n s&amp;#7869; gi&amp;#7843;m &amp;#273;i m&amp;#7897;t n&amp;#7917;a s&amp;#7889; l&amp;#432;&amp;#7907;ng ph&amp;#7847;n t&amp;#7917;, chia nh&amp;#7887; m&amp;#7843;ng l&amp;#224;m 2 ph&amp;#7847;n, lo&amp;#7841;i b&amp;#7887; 1 ph&amp;#7847;n v&amp;#224; t&amp;#237;nh to&amp;#225;n ti&amp;#7871;p tr&amp;#234;n ph&amp;#7847;n c&amp;#242;n l&amp;#7841;i c&amp;#7911;a m&amp;#7843;ng. Trong tr&amp;#432;&amp;#7901;ng h&amp;#7907;p t&amp;#7889;t nh&amp;#7845;t th&amp;#236; gi&amp;#225; tr&amp;#7883; c&amp;#7847;n t&amp;#236;m s&amp;#7869; n&amp;#7857;m &amp;#7903; gi&amp;#7919;a m&amp;#7843;ng, nh&amp;#432;ng trong tr&amp;#432;&amp;#7901;ng h&amp;#7907;p x&amp;#7845;u nh&amp;#7845;t th&amp;#236; n&amp;#243; s&amp;#7869; n&amp;#7857;m &amp;#7903; &amp;#273;&amp;#7847;u ho&amp;#7863;c cu&amp;#7889;i m&amp;#7843;ng. Gi&amp;#7843; s&amp;#7917; m&amp;#236;nh &amp;#273;i t&amp;#236;m s&amp;#7889; 1 trong m&amp;#7843;ng, n&amp;#243; l&amp;#224; con s&amp;#7889; &amp;#7903; &amp;#273;&amp;#7847;u m&amp;#7843;ng t&amp;#432;&amp;#417;ng &amp;#7913;ng v&amp;#7899;i tr&amp;#432;&amp;#7901;ng h&amp;#7907;p x&amp;#7845;u nh&amp;#7845;t. Nh&amp;#432; &amp;#273;&amp;#227; th&amp;#7845;y m&amp;#236;nh s&amp;#7869; m&amp;#7845;t 3 l&amp;#7847;n l&amp;#7863;p &amp;#273;&amp;#7875; c&amp;#243; th&amp;#7875; c&amp;#243; th&amp;#7875; t&amp;#236;m &amp;#273;&amp;#432;&amp;#7907;c gi&amp;#225; tr&amp;#7883; trong m&amp;#7843;ng c&amp;#243; 8 ph&amp;#7847;n t&amp;#7917;.&amp;#160;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;img src=&quot;../images/bai-viet/backend/big-o-do-phuc-tap-thuat-toan/bodpttt1699776408481.gif&quot; alt=&quot;&quot; width=&quot;800&quot; height=&quot;789&quot; /&gt;&lt;/p&gt;
&lt;h2 dir=&quot;ltr&quot;&gt;O(1) l&amp;#224; g&amp;#236;?&lt;/h2&gt;
&lt;p&gt;&lt;img src=&quot;../images/bai-viet/backend/big-o-do-phuc-tap-thuat-toan/bodpttt1699777083255.gif&quot; alt=&quot;&quot; width=&quot;795&quot; height=&quot;784&quot; /&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;O(1) l&amp;#224; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p h&amp;#7857;ng s&amp;#7889;, n&amp;#243; l&amp;#224; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p t&amp;#7889;t nh&amp;#7845;t, ch&amp;#7881; c&amp;#7847;n th&amp;#7921;c hi&amp;#7879;n m&amp;#7897;t thao t&amp;#225;c m&amp;#236;nh &amp;#273;&amp;#227; c&amp;#243; ngay k&amp;#7871;t qu&amp;#7843;. &amp;#7902; v&amp;#237; d&amp;#7909; b&amp;#234;n d&amp;#432;&amp;#7899;i m&amp;#236;nh c&amp;#243; m&amp;#7897;t h&amp;#224;m sum, h&amp;#224;m sum n&amp;#224;y s&amp;#7869; nh&amp;#7853;n 2 input l&amp;#224; n v&amp;#224; m, tuy n v&amp;#224; m c&amp;#243; th&amp;#7875; thay &amp;#273;&amp;#7893;i nh&amp;#432;ng c&amp;#361;ng ch&amp;#7881; m&amp;#7845;t m&amp;#7897;t thao t&amp;#225;c t&amp;#237;nh to&amp;#225;n th&amp;#236; m&amp;#236;nh c&amp;#243; th&amp;#7875; c&amp;#243; k&amp;#7871;t qu&amp;#7843; ng&amp;#224;y, ho&amp;#7863;c vi&amp;#7879;c truy c&amp;#7853;p v&amp;#224;o m&amp;#7897;t dictionary, truy c&amp;#7853;p ngay l&amp;#7853;p t&amp;#7913;c b&amp;#7857;ng key m&amp;#224; kh&amp;#244;ng c&amp;#7847;n ph&amp;#7843;i l&amp;#7863;p qua m&amp;#7843;ng th&amp;#236; &amp;#273;&amp;#226;y l&amp;#224; &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p O(1), &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p &amp;#273;&amp;#432;&amp;#7907;c xem l&amp;#224; ho&amp;#224;n h&amp;#7843;o nh&amp;#7845;t.&amp;#160;&lt;/p&gt;
&lt;h2 dir=&quot;ltr&quot;&gt;T&amp;#243;m l&amp;#7841;i&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;- &amp;#272;&amp;#7875; vi&amp;#7871;t thu&amp;#7853;t to&amp;#225;n hi&amp;#7879;u qu&amp;#7843; th&amp;#236; n&amp;#234;n h&amp;#7841;n ch&amp;#7871; s&amp;#7917; d&amp;#7909;ng c&amp;#225;c v&amp;#242;ng l&amp;#7863;p l&amp;#7891;ng nhau, n&amp;#243; s&amp;#7869; l&amp;#224;m t&amp;#259;ng &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p c&amp;#7911;a thu&amp;#7853;t to&amp;#225;n v&amp;#224; th&amp;#7901;i gian th&amp;#7921;c thi s&amp;#7869; l&amp;#226;u h&amp;#417;n.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;- Ch&amp;#7885;n c&amp;#7845;u tr&amp;#250;c d&amp;#7919; li&amp;#7879;u ph&amp;#249; h&amp;#7907;p, &amp;#7903; m&amp;#7895;i b&amp;#224;i to&amp;#225;n kh&amp;#225;c nhau m&amp;#236;nh n&amp;#234;n xem x&amp;#233;t nh&amp;#7919;ng c&amp;#7845;u tr&amp;#250;c d&amp;#7919; li&amp;#7879;u n&amp;#224;o hi&amp;#7879;u qu&amp;#7843; nh&amp;#7845;t &amp;#273;&amp;#7875; &amp;#225;p d&amp;#7909;ng v&amp;#237; d&amp;#7909; nh&amp;#432; Dictionary, Hash Table, Linked List, Graph v.v.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;- Th&amp;#7921;c hi&amp;#7879;n ghi nh&amp;#7899; c&amp;#225;c gi&amp;#225; tr&amp;#7883; n&amp;#7871;u c&amp;#7847;n thi&amp;#7871;t, tr&amp;#225;nh vi&amp;#7879;c t&amp;#237;nh to&amp;#225;n l&amp;#7863;p l&amp;#7841;i.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;- &amp;#193;p d&amp;#7909;ng ph&amp;#432;&amp;#417;ng ph&amp;#225;p chia &amp;#273;&amp;#7875; tr&amp;#7883; nh&amp;#432; v&amp;#237; d&amp;#7909; c&amp;#7911;a thu&amp;#7853;t to&amp;#225;n Binary Search v&amp;#7899;i &amp;#273;&amp;#7897; ph&amp;#7913;c t&amp;#7841;p l&amp;#224; O(log n).&lt;/p&gt;
&lt;p&gt;&amp;#160;&lt;/p&gt;
&lt;/body&gt;
&lt;/html&gt;

Big O là khái niệm để đo lường độ hiệu quả của thuật toán khi chạy ở tình huống xấu nhất với lượng input lớn. Là một developer thì việc hiểu về Big O sẽ mang lại rất nhiều lợi ích trong quá trình code, nếu nhận ra độ phức tạp của thuật toán quá lớn thì developer có thể điều chỉnh lại code của mình và đi theo hướng khác để tối ưu hóa giải thuật.

Big O độ phức tạp thuật toán

&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;div class=&quot;mce-toc&quot;&gt;
&lt;h2&gt;M&amp;#7909;c L&amp;#7909;c:&lt;/h2&gt;
&lt;ul&gt;
&lt;li&gt;&lt;a href=&quot;#mcetoc_1dnq4b8n344&quot;&gt;C&amp;#7845;u tr&amp;#250;c project&lt;/a&gt;&lt;/li&gt;
&lt;li&gt;&lt;a href=&quot;#mcetoc_1dnq4b8n345&quot;&gt;Code Rest Api Golang&lt;/a&gt;&lt;/li&gt;
&lt;li&gt;&lt;a href=&quot;#mcetoc_1dnq4b8n346&quot;&gt;Ki&amp;#7875;m Tra K&amp;#7871;t Qu&amp;#7843;&lt;/a&gt;&lt;/li&gt;
&lt;li&gt;&lt;a href=&quot;#mcetoc_1dnq4b8n347&quot;&gt;T&amp;#7893;ng k&amp;#7871;t:&lt;/a&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;/div&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#272;&amp;#7875; ti&amp;#7871;p c&amp;#7853;n v&amp;#7899;i Golang m&amp;#7897;t c&amp;#225;ch nhanh ch&amp;#243;ng h&amp;#417;n, ch&amp;#250;ng ta s&amp;#7869; x&amp;#226;y d&amp;#7921;ng m&amp;#7897;t REST API c&amp;#417; b&amp;#7843;n v&amp;#7899;i Golang nh&amp;#233;.&lt;/p&gt;
&lt;h2 id=&quot;mcetoc_1dnq4b8n344&quot; dir=&quot;ltr&quot;&gt;C&amp;#7845;u tr&amp;#250;c project&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;Ch&amp;#250;ng ta h&amp;#227;y t&amp;#7841;o c&amp;#7845;u tr&amp;#250;c th&amp;#432; m&amp;#7909;c nh&amp;#432; h&amp;#236;nh b&amp;#234;n d&amp;#432;&amp;#7899;i, project n&amp;#224;y c&amp;#243; t&amp;#234;n GolangRestApi c&amp;#225;c b&amp;#7841;n c&amp;#243; th&amp;#7875; clone v&amp;#7873; v&amp;#7899;i &amp;#273;&amp;#432;&amp;#7901;ng link sau: &lt;span style=&quot;color: #3366ff;&quot;&gt;&lt;a style=&quot;color: #3366ff; text-decoration: underline;&quot; href=&quot;https://github.com/PhongVX/golang-rest-api/tree/golang-rest-api-basic&quot; target=&quot;_blank&quot; rel=&quot;noopener&quot;&gt;Github&lt;/a&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Sau khi clone v&amp;#7873; c&amp;#225;c b&amp;#7841;n nh&amp;#7899; &amp;#273;&amp;#7893;i t&amp;#234;n project th&amp;#224;nh GolangRestApi v&amp;#224; v&amp;#224;o GOPATH r&amp;#7891;i copy v&amp;#224;o th&amp;#432; m&amp;#7909;c src, c&amp;#225;ch c&amp;#224;i &amp;#273;&amp;#7863;t v&amp;#224; setup d&amp;#7921; &amp;#225;n Golang c&amp;#225;c b&amp;#7841;n c&amp;#243; th&amp;#7875; tham kh&amp;#7843;o chi ti&amp;#7871;t t&amp;#7841;i b&amp;#224;i vi&amp;#7871;t n&amp;#224;y c&amp;#7911;a m&amp;#236;nh:&amp;#160;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;span style=&quot;color: #3366ff;&quot;&gt;https://anhlamweb.com/bai-viet-64/hoc-golang-tu-con-so-0-phan-1-cai-dat-golang-tren-linux-va-windows.html&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;span style=&quot;color: #3366ff;&quot;&gt;&lt;img style=&quot;margin-top: 0px; display: block; margin-left: auto; margin-right: auto; max-width: 257px;&quot; src=&quot;https://lh4.googleusercontent.com/pCzc3bZeqYfcn7eo_xnAxuhrOJIkrem389a2T4HijWbfbmx5XBiwvxrC5CVPmrEEyqAu68tnu6H4xoRF5ihPXVi6Jnh_zWtvTYwsk_OKbI-EzbiSapcUMdnYTLBFN5umnFHMTs6j&quot; width=&quot;257&quot; height=&quot;226&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;h2 id=&quot;mcetoc_1dnq4b8n345&quot; dir=&quot;ltr&quot;&gt;Code Rest Api Golang&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;entities/user.go&lt;/strong&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Khai b&amp;#225;o c&amp;#7845;u tr&amp;#250;c c&amp;#7911;a m&amp;#7897;t th&amp;#7921;c th&amp;#7875; User. User s&amp;#7869; c&amp;#243; h&amp;#224;m ToString &amp;#273;&amp;#7875; xu&amp;#7845;t th&amp;#244;ng tin chi ti&amp;#7871;t c&amp;#7911;a User &amp;#273;&amp;#243; ra.&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;package entities
 
import (
    &quot;fmt&quot;
)
 
type User struct {
    Id       string `json:&quot;id&quot;`
    Name     string `json:&quot;name&quot;`
    Password string `json:&quot;password&quot;`
}
 
func (user User) ToString() string {
    return fmt.Sprintf(&quot;id: %s\nName: %s\nPassword: %s\n&quot;, user.Id, user.Name, user.Password)
}
&lt;/code&gt;&lt;/pre&gt;
&lt;p&gt;&lt;strong&gt;&lt;span id=&quot;docs-internal-guid-5d6c8bca-7fff-ae04-1adc-dfdfbffff1fc&quot;&gt;models/userModel.go&lt;/span&gt;&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;span id=&quot;docs-internal-guid-89978eb3-7fff-6e64-ea6f-1b49e39fc04e&quot;&gt;&amp;#272;&amp;#7883;nh ngh&amp;#297;a c&amp;#225;c h&amp;#224;m c&amp;#417; b&amp;#7843;n nh&amp;#432; CreateUser, UpdateUser, FindUser, DeleteUser v&amp;#224; GetAllUser. listUser d&amp;#249;ng &amp;#273;&amp;#7875; ch&amp;#432;a th&amp;#244;ng tin c&amp;#7911;a c&amp;#225;c User, thay v&amp;#236; &amp;#273;&amp;#7875; khai b&amp;#225;o listUser nh&amp;#432; v&amp;#7853;y ch&amp;#250;ng ta c&amp;#243; th&amp;#7875; connect t&amp;#7899;i&amp;#160; database v&amp;#224; th&amp;#7921;c hi&amp;#7879;n c&amp;#225;c thao t&amp;#225;c nh&amp;#432; tr&amp;#234;n, nh&amp;#432;ng &amp;#273;&amp;#7875; d&amp;#7877; hi&amp;#7875;u v&amp;#224; r&amp;#245; r&amp;#224;ng h&amp;#417;n th&amp;#236; &amp;#7903; b&amp;#224;i vi&amp;#7871;t n&amp;#224;y ch&amp;#250;ng ta s&amp;#7869; th&amp;#7921;c hi&amp;#7879;n theo c&amp;#225;ch &amp;#273;&amp;#417;n gi&amp;#7843;n n&amp;#224;y tr&amp;#432;&amp;#7899;c.&lt;/span&gt;&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;package models
 
import (
    &quot;GolangRestApi/entities&quot;
    &quot;errors&quot;
)
 
var (
    listUser = make([]*entities.User, 0)
)
 
func CreateUser(user *entities.User) bool {
    if user.Id != &quot;&quot; &amp;amp;&amp;amp; user.Name != &quot;&quot; &amp;amp;&amp;amp; user.Password != &quot;&quot; {
        if userF, _ := FindUser(user.Id); userF == nil {
            listUser = append(listUser, user)
            return true
        }
    }
    return false
}

func UpdateUser(eUser *entities.User) bool {
    for index, user := range listUser {
        if user.Id == eUser.Id {
            listUser[index] = eUser
            return true
        }
    }
    return false
}

func FindUser(id string) (*entities.User, error) {
    for _, user := range listUser {
        if user.Id == id {
            return user, nil
        }
    }
    return nil, errors.New(&quot;User does not exist&quot;)
}

func DeleteUser(id string) bool {
    for index, user := range listUser {
        if user.Id == id {
            copy(listUser[index:], listUser[index+1:])
            listUser[len(listUser)-1] = &amp;amp;entities.User{}
            listUser = listUser[:len(listUser)-1]
            return true
        }
    }
    return false
}

func GetAllUser() []*entities.User {
    return listUser
}
&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;apis/userapi/userApi.go&lt;/strong&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#7902; file n&amp;#224;y l&amp;#224; c&amp;#225;c h&amp;#224;m x&amp;#7917; l&amp;#253; c&amp;#225;c http request v&amp;#224; ch&amp;#7883;u tr&amp;#225;ch nhi&amp;#7879;m tr&amp;#7843; v&amp;#7873; k&amp;#7871;t qu&amp;#7843; cho ng&amp;#432;&amp;#7901;i d&amp;#249;ng b&amp;#7857;ng http response.&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;package userapi
 
import (
    &quot;GolangRestApi/entities&quot;
    &quot;GolangRestApi/models&quot;
    &quot;encoding/json&quot;
    &quot;net/http&quot;
)
 
func FindUser(response http.ResponseWriter, request *http.Request) {
    ids, ok := request.URL.Query()[&quot;id&quot;]
    if !ok || len(ids) &amp;lt; 1 {
        responseWithError(response, http.StatusBadRequest, &quot;Url Param id is missing&quot;)
        return
    }
    user, err := models.FindUser(ids[0])
    if err != nil {
        responseWithError(response, http.StatusBadRequest, err.Error())
        return
    }
    responseWithJSON(response, http.StatusOK, user)
}
 
func GetAll(response http.ResponseWriter, request *http.Request) {
    users := models.GetAllUser()
    responseWithJSON(response, http.StatusOK, users)
}
 
func CreateUser(response http.ResponseWriter, request *http.Request) {
    var user entities.User
    err := json.NewDecoder(request.Body).Decode(&amp;amp;user)
    if err != nil {
        responseWithError(response, http.StatusBadRequest, err.Error())
    } else {
        result := models.CreateUser(&amp;amp;user)
        if !result {
            responseWithError(response, http.StatusBadRequest, &quot;Could not create user&quot;)
            return
        }
        responseWithJSON(response, http.StatusOK, user)
    }
}

func UpdateUser(response http.ResponseWriter, request *http.Request) {
    var user entities.User
    err := json.NewDecoder(request.Body).Decode(&amp;amp;user)
    if err != nil {
        responseWithError(response, http.StatusBadRequest, err.Error())
    } else {
        result := models.UpdateUser(&amp;amp;user)
        if !result {
            responseWithError(response, http.StatusBadRequest, &quot;Could not update user&quot;)
            return
        }
        responseWithJSON(response, http.StatusOK, &quot;Update user successfully&quot;)
    }
}
 
func Delete(response http.ResponseWriter, request *http.Request) {
    ids, ok := request.URL.Query()[&quot;id&quot;]
    if !ok || len(ids) &amp;lt; 1 {
        responseWithError(response, http.StatusBadRequest, &quot;Url Param id is missing&quot;)
        return
    }
    result := models.DeleteUser(ids[0])
    if !result {
        responseWithError(response, http.StatusBadRequest, &quot;Could not delete user&quot;)
        return
    }
    responseWithJSON(response, http.StatusOK, &quot;Delete user successfully&quot;)
}
 
func responseWithError(response http.ResponseWriter, statusCode int, msg string) {
    responseWithJSON(response, statusCode, map[string]string{
        &quot;error&quot;: msg,
    })
}
 
func responseWithJSON(response http.ResponseWriter, statusCode int, data interface{}) {
    result, _ := json.Marshal(data)
    response.Header().Set(&quot;Content-Type&quot;, &quot;application/json&quot;)
    response.WriteHeader(statusCode)
    response.Write(result)
}
 
&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;Main.go&lt;/strong&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#272;&amp;#7875; x&amp;#226;y d&amp;#7921;ng m&amp;#7897;t REST Api Server th&amp;#236; &amp;#7903; &amp;#273;&amp;#226;y ch&amp;#250;ng ta s&amp;#7917; d&amp;#7909;ng mux v&amp;#224; t&amp;#7841;o m&amp;#7897;t router &amp;#273;&amp;#7875; n&amp;#243; th&amp;#7921;c hi&amp;#7879;n vi&amp;#7879;c handle request nh&amp;#432; sau.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Server s&amp;#7869; l&amp;#7855;ng nghe &amp;#7903; port 5000.&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;package main
 
import (
    &quot;GolangRestApi/apis/userapi&quot;
    &quot;net/http&quot;
 
    &quot;github.com/gorilla/mux&quot;
)
 
func main() {
    router := mux.NewRouter()
 
    router.HandleFunc(&quot;/api/v1/user/find&quot;, userapi.FindUser).Methods(&quot;GET&quot;)
    router.HandleFunc(&quot;/api/v1/user/getall&quot;, userapi.GetAll).Methods(&quot;GET&quot;)
    router.HandleFunc(&quot;/api/v1/user/create&quot;, userapi.CreateUser).Methods(&quot;POST&quot;)
    router.HandleFunc(&quot;/api/v1/user/update&quot;, userapi.UpdateUser).Methods(&quot;PUT&quot;)
    router.HandleFunc(&quot;/api/v1/user/delete&quot;, userapi.Delete).Methods(&quot;DELETE&quot;)
 
    err := http.ListenAndServe(&quot;:5000&quot;, router)
    if err != nil {
        panic(err)
    }
}
&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span style=&quot;font-size: 11pt; font-family: Arial; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;&quot;&gt;Ch&amp;#7841;y ch&amp;#432;&amp;#417;ng tr&amp;#236;nh b&amp;#7857;ng l&amp;#7879;nh&lt;/span&gt;&lt;span id=&quot;docs-internal-guid-ee27037a-7fff-b446-3980-2f7d2c9a1e0d&quot;&gt;&lt;/span&gt;&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;go run main.go&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot; style=&quot;line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;&quot;&gt;&lt;span id=&quot;docs-internal-guid-6d6d576b-7fff-e5d9-5dab-c2119c6fb562&quot;&gt;&lt;img style=&quot;display: block; margin-left: auto; margin-right: auto; max-width: 444px;&quot; src=&quot;https://lh4.googleusercontent.com/9PIvGOSQLWOGdHCgUgq1ml9R5q_FHxVO86Ki7uliT7uGi33PlfWxWwhhH5u0aLMoeZhupDWdWDSj5C3u2y1PQ_NrV7eC3r-0pmNR_N4f_fpd2-kYTgP1T85TYZs7y5zxBRO4M5RE&quot; width=&quot;444&quot; height=&quot;225&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;h2 id=&quot;mcetoc_1dnq4b8n346&quot; dir=&quot;ltr&quot;&gt;Ki&amp;#7875;m Tra K&amp;#7871;t Qu&amp;#7843;&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#272;&amp;#7875; ki&amp;#7875;m tra k&amp;#7871;t qu&amp;#7843; ch&amp;#250;ng ta s&amp;#7869; s&amp;#7917; d&amp;#7909;ng Postman nh&amp;#233;, b&amp;#7841;n c&amp;#243; th&amp;#7875; v&amp;#224;o th&amp;#432; m&amp;#7909;c assets v&amp;#224; import file GolangRestApi.postman_collection.json v&amp;#224;o &amp;#273;&amp;#7875; test cho nhanh.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;T&amp;#7841;o m&amp;#7899;i User.&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;span id=&quot;docs-internal-guid-3718afdc-7fff-0fdb-8f4a-0e2bcf6f41ba&quot;&gt;&lt;img src=&quot;https://lh4.googleusercontent.com/zozOh6Wc8KkuE3mhXtA8dW-kxtMlTe6myVyG2jTC2qPIk4jscNUl6mNmEmjiIoctDxRQ-AFpv5RNuNq1f5RjwADvoMG2Y17jk5fL6Dn27UoGd_u1tffJi3tGKfQ7P_4OsUfenEDB&quot; width=&quot;804&quot; height=&quot;388&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;L&amp;#7845;y danh s&amp;#225;ch c&amp;#225;c User&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;span id=&quot;docs-internal-guid-bba5ea0e-7fff-e827-03e9-0ccf97628085&quot;&gt;&lt;img src=&quot;https://lh5.googleusercontent.com/bWO1oMK3HyzbxNBAWrRiR5eV4e9-Zc7fXtwwJvH6ASqq4xEV0zMYOsblSuN2jlRDRvq20IgEg4yaFcTdJH81Ym9u1t7EAL-POoSddS0x0wtauJDv-Torsn751Ecavbdrm69uYuu5&quot; width=&quot;803&quot; height=&quot;350&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;T&amp;#236;m ki&amp;#7871;m m&amp;#7897;t User&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;span id=&quot;docs-internal-guid-1e0ad493-7fff-438c-2c2d-d227a29c8d35&quot;&gt;&lt;img src=&quot;https://lh6.googleusercontent.com/pghSwMTOCKDDxUoj7shPbTyMmZJEVOEegyluqFAtMLmmwKD8e4g2Zj6ZJFBn4f8-N-69F-4bDNP2ilRh4_TGBeyv_D_vQ9rxTPAOo1FYqFNb385DJKaW7mszLj_UEemYkhMnHDBj&quot; width=&quot;802&quot; height=&quot;356&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;C&amp;#7853;p nh&amp;#7853;t User&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;span id=&quot;docs-internal-guid-56fa0bf6-7fff-5ddb-e342-6564b2091207&quot;&gt;&lt;img src=&quot;https://lh3.googleusercontent.com/BSB7iJnzqFFf_zFBCYqAUCV0VqSlaPJ9WVv14wxc5uV1VJh-ToQ3C0auHc4soVgg7WAX5KkhiG8xvTEzRSQp84gceRprZw3albJoDziqDO6FiBbuOW9hExMoJ3kJoVAA9vxSHt3l&quot; width=&quot;801&quot; height=&quot;380&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Sau khi update user ch&amp;#250;ng ta h&amp;#227;y ki&amp;#7875;m tra l&amp;#7841;i th&amp;#244;ng tin v&amp;#7915;a &amp;#273;&amp;#432;&amp;#7907;c update.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;span id=&quot;docs-internal-guid-4ca50128-7fff-92a8-55ab-7a03fb7f77f3&quot;&gt;&lt;img src=&quot;https://lh5.googleusercontent.com/pox5h_LhYmLDFIQ_8YZ6MbEsJIr2t5XD3G0QRqN4Iw1DULeRPmeykmQKiL1MPRZNhy-xCUAkhb1qb4kZinrMTbIdCS18yrCYA7HRl9CyQ5kRj1pK1H49AjsnMrBUpRtCFX6eKe4q&quot; width=&quot;798&quot; height=&quot;367&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;X&amp;#243;a m&amp;#7897;t User&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;&lt;span id=&quot;docs-internal-guid-9cd601fd-7fff-b8a4-6664-3e19d8cc1ab3&quot;&gt;&lt;img src=&quot;https://lh3.googleusercontent.com/9gdwKSL9yBn1Dv4VJTKqunlTfmysqEnqPZL6UjnGL0TvgHOjB-kYKdbzBerui1w_4Ejxwu7po3ZFeddV_OcUJxk3U63sT2HBTpP4V853eSVSHYh2176rnQA9JHqQVfOMgoAYXVM4&quot; width=&quot;807&quot; height=&quot;295&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Sau khi delete user ch&amp;#250;ng ta h&amp;#227;y ki&amp;#7875;m tra l&amp;#7841;i danh s&amp;#225;ch, nh&amp;#432; h&amp;#236;nh b&amp;#234;n d&amp;#432;&amp;#7899;i sau khi delete user &amp;#273;i th&amp;#236; danh s&amp;#225;ch l&amp;#224; r&amp;#7895;ng.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;span id=&quot;docs-internal-guid-a7e45f17-7fff-e13f-7aba-a90aa3a32019&quot;&gt;&lt;img src=&quot;https://lh4.googleusercontent.com/GGzIRro5tFyu7UtOmR5m_p4Q5IARFEe6zgqAYErfMvTmP1T4qY5HgZhkGNOn4_BFoFN2xRSuXniotjI0hlwQzhzJQcJ271eR4g0LbkPRTsaOqAwlkNZYm5ZWi7LOhCj2Q3TJUde1&quot; width=&quot;810&quot; height=&quot;318&quot; /&gt;&lt;/span&gt;&lt;/p&gt;
&lt;h2 id=&quot;mcetoc_1dnq4b8n347&quot; dir=&quot;ltr&quot;&gt;T&amp;#7893;ng k&amp;#7871;t:&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;Ch&amp;#250;ng ta &amp;#273;&amp;#227; t&amp;#7853;p l&amp;#224;m quen v&amp;#7899;i Golang v&amp;#224; Rest Api trong Golang, &amp;#7903; b&amp;#224;i ti&amp;#7871;p theo ch&amp;#250;ng ta s&amp;#7869; t&amp;#236;m hi&amp;#7875;u ti&amp;#7871;p v&amp;#7873; x&amp;#225;c th&amp;#7921;c Rest Api s&amp;#7917; d&amp;#7909;ng Json Web Token nh&amp;#233;.&lt;/p&gt;
&lt;/body&gt;
&lt;/html&gt;

Để tiếp cận với Golang một cách nhanh chóng hơn, chúng ta sẽ xây dựng một REST API cơ bản với Golang nhé.

Xây dựng REST API cơ bản trong Golang

reactjs co gi loi hai ma lazada, tiki, shopee, sendo va cac trang thuong mai dien tu lon khac deu dang su dung?

ReactJS Có Gì Lợi Hại Mà Lazada, Tiki, Shopee, Sendo Và Các Trang Thương Mại Điện Tử Lớn Khác Đều Đang Sử Dụng?

&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
&lt;/head&gt;
&lt;body&gt;
&lt;div class=&quot;mce-toc&quot;&gt;
&lt;h2&gt;M&amp;#7909;c l&amp;#7909;c&lt;/h2&gt;
&lt;ul&gt;
&lt;li&gt;&lt;a href=&quot;#mcetoc_1dudut73g1&quot;&gt;Gi&amp;#7899;i thi&amp;#7879;u v&amp;#7873; Go Mod&lt;/a&gt;&lt;/li&gt;
&lt;li&gt;&lt;a href=&quot;#mcetoc_1dudut73g2&quot;&gt;S&amp;#7917; d&amp;#7909;ng Go Mod&lt;/a&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;/div&gt;
&lt;h2 id=&quot;mcetoc_1dudut73g1&quot; dir=&quot;ltr&quot;&gt;Gi&amp;#7899;i thi&amp;#7879;u v&amp;#7873; Go Mod&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;&amp;#272;&amp;#7875; qu&amp;#7843;n l&amp;#253; c&amp;#225;c modules trong Go m&amp;#7897;t c&amp;#225;ch ti&amp;#7879;n l&amp;#7907;i v&amp;#224; d&amp;#7877; d&amp;#224;ng h&amp;#417;n, t&amp;#7915; phi&amp;#234;n b&amp;#7843;n Go 1.11 &amp;#273;&amp;#7897;i ng&amp;#361; Go &amp;#273;&amp;#227; cho ra m&amp;#7855;t Go Modules.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Ch&amp;#250;ng ta c&amp;#243; th&amp;#7875; s&amp;#7917; d&amp;#7909;ng Go Modules, g&amp;#7885;i t&amp;#7855;t l&amp;#224; Go Mod &amp;#273;&amp;#7875; install c&amp;#225;c g&amp;#243;i module m&amp;#7897;t c&amp;#225;ch t&amp;#7921; &amp;#273;&amp;#7897;ng khi ch&amp;#250;ng ta th&amp;#7921;c hi&amp;#7879;n th&amp;#7921;c thi ch&amp;#432;&amp;#417;ng tr&amp;#236;nh.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;N&amp;#7871;u kh&amp;#244;ng c&amp;#243; Go Modules th&amp;#236; anh em c&amp;#243; nh&amp;#7899; m&amp;#7895;i l&amp;#7847;n clone project v&amp;#7873; &amp;#273;&amp;#7875; tham kh&amp;#7843;o l&amp;#224; ph&amp;#7843;i s&amp;#7917; d&amp;#7909;ng l&amp;#7879;nh &amp;#8220;&lt;strong&gt;go get&lt;/strong&gt;&amp;#8221; &amp;#273;&amp;#7875; t&amp;#7843;i th&amp;#432; vi&amp;#7879;n, r&amp;#7845;t chi l&amp;#224; m&amp;#7845;t th&amp;#7901;i gian lu&amp;#244;n, n&amp;#7871;u project &amp;#237;t th&amp;#432; vi&amp;#7879;n th&amp;#236; kh&amp;#244;ng n&amp;#243;i, project m&amp;#224; s&amp;#7917; d&amp;#7909;ng nhi&amp;#7873;u module th&amp;#432; vi&amp;#7879;n th&amp;#236; t&amp;#7843;i v&amp;#7873; b&amp;#7857;ng &amp;#8220;go get&amp;#8221; s&amp;#7869; r&amp;#7845;t l&amp;#224; n&amp;#7843;n.&lt;/p&gt;
&lt;h2 id=&quot;mcetoc_1dudut73g2&quot; dir=&quot;ltr&quot;&gt;S&amp;#7917; d&amp;#7909;ng Go Mod&lt;/h2&gt;
&lt;p dir=&quot;ltr&quot;&gt;Anh em c&amp;#243; th&amp;#7875; t&amp;#7843;i code tham kh&amp;#7843;o v&amp;#224; th&amp;#7921;c h&amp;#224;nh v&amp;#7899;i project Go &amp;#7903; &amp;#273;&amp;#432;&amp;#7901;ng link sau &amp;#273;&amp;#226;y: &lt;span style=&quot;color: #3366ff;&quot;&gt;&lt;a style=&quot;color: #3366ff;&quot; href=&quot;https://github.com/PhongVX/golang-rest-api.git&quot;&gt;Github&lt;/a&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Project tr&amp;#234;n m&amp;#236;nh x&amp;#226;y d&amp;#7921;ng trong &lt;strong&gt;GOPATH&lt;/strong&gt; v&amp;#7899;i link h&amp;#432;&amp;#7899;ng d&amp;#7851;n chi ti&amp;#7871;t t&amp;#7841;i: &lt;span style=&quot;color: #3366ff;&quot;&gt;https://anhlamweb.com/bai-viet-70/xay-dung-rest-api-co-ban-trong-golang.html&lt;/span&gt;&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;V&amp;#224; gi&amp;#7901; t&amp;#7915; project &amp;#273;&amp;#243; m&amp;#236;nh s&amp;#7869; chuy&amp;#7875;n qua d&amp;#249;ng Go Modules &amp;#273;&amp;#7875; qu&amp;#7843;n l&amp;#253; c&amp;#225;c module th&amp;#432; vi&amp;#7879;n d&amp;#7877; d&amp;#224;ng h&amp;#417;n nha.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Anh em c&amp;#243; th&amp;#7875; &amp;#273;&amp;#7875; &amp;#253;, sau khi clone project v&amp;#7873; v&amp;#7899;i &amp;#273;&amp;#432;&amp;#7901;ng link Git &amp;#7903; tr&amp;#234;n th&amp;#236; c&amp;#243; 2 file go.mod v&amp;#224; go.sum.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;go.mod&lt;/strong&gt; : &amp;#272;&amp;#7883;nh ngh&amp;#297;a &amp;#273;&amp;#432;&amp;#7901;ng d&amp;#7851;n c&amp;#7911;a c&amp;#225;c module.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;go.sum:&lt;/strong&gt; &amp;#272;&amp;#7875; l&amp;#432;u v&amp;#7871;t version c&amp;#7911;a th&amp;#432; vi&amp;#7879;n m&amp;#224; project &amp;#273;ang s&amp;#7917; d&amp;#7909;ng.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;Anh em nh&amp;#7899; check l&amp;#7841;i version go m&amp;#224; m&amp;#236;nh &amp;#273;ang s&amp;#7917; d&amp;#7909;ng nh&amp;#233;, n&amp;#7871;u &lt;strong&gt;Go 1.11 tr&amp;#7903; l&amp;#234;n&lt;/strong&gt; th&amp;#236; m&amp;#7899;i c&amp;#243; Go Modules nh&amp;#233;.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;V&amp;#7899;i vi&amp;#7879;c s&amp;#7917; d&amp;#7909;ng Go mod, &lt;strong&gt;&amp;#273;&amp;#432;&amp;#7901;ng d&amp;#7851;n t&amp;#7899;i project ph&amp;#7843;i n&amp;#7857;m ngo&amp;#224;i th&amp;#432; m&amp;#7909;c src c&amp;#7911;a GOPATH&lt;/strong&gt; ho&amp;#7863;c anh em c&amp;#243; th&amp;#7875; &lt;strong&gt;x&amp;#243;a bi&amp;#7871;n m&amp;#244;i tr&amp;#432;&amp;#7901;ng c&amp;#7911;a GOPATH&lt;/strong&gt; &amp;#273;i lu&amp;#244;n c&amp;#361;ng &amp;#273;&amp;#432;&amp;#7907;c.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;B&amp;#432;&amp;#7899;c 1:&lt;/strong&gt; sau khi clone project v&amp;#7873; n&amp;#7871;u anh em mu&amp;#7889;n ch&amp;#7841;y ngay ch&amp;#432;&amp;#417;ng tr&amp;#236;nh th&amp;#236; c&amp;#7913; vi&amp;#7879;c ch&amp;#7841;y l&amp;#7879;nh &lt;strong&gt;go run main.go&lt;/strong&gt; l&amp;#224; &amp;#273;&amp;#432;&amp;#7907;c, go mod s&amp;#7869; t&amp;#7921; &amp;#273;&amp;#7897;ng t&amp;#7843;i c&amp;#225;c g&amp;#243;i module v&amp;#7873; cho anh em lu&amp;#244;n.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;B&amp;#432;&amp;#7899;c 2:&lt;/strong&gt; B&amp;#432;&amp;#7899;c n&amp;#224;y anh em mu&amp;#7889;n t&amp;#7921; tay m&amp;#236;nh bi&amp;#7875;u di&amp;#7877;n k&amp;#7929; thu&amp;#7853;t, th&amp;#236; h&amp;#227;y x&amp;#243;a &lt;strong&gt;go.mod&lt;/strong&gt; v&amp;#224; &lt;strong&gt;go.sum&lt;/strong&gt; &amp;#273;i sau &amp;#273;&amp;#243; ch&amp;#7841;y l&amp;#7879;nh:&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;go mod init&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot;&gt;Sau khi ch&amp;#7841;y l&amp;#7879;nh tr&amp;#234;n th&amp;#236; file go.mod &amp;#273;&amp;#432;&amp;#7907;c kh&amp;#7903;i t&amp;#7841;o.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;N&amp;#7897;i dung trong file go.mod&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;module github.com/PhongVX/golang-rest-api

go 1.12

require github.com/gorilla/mux v1.7.3 // indirect&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot;&gt;&lt;strong&gt;B&amp;#432;&amp;#7899;c 3:&lt;/strong&gt; Ch&amp;#7841;y ch&amp;#432;&amp;#417;ng tr&amp;#236;nh v&amp;#224; t&amp;#7921; &amp;#273;&amp;#7897;ng t&amp;#7843;i c&amp;#225;c module b&amp;#7857;ng l&amp;#7879;nh:&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;go run main.go&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot;&gt;Sau khi ch&amp;#7841;y ch&amp;#432;&amp;#417;ng tr&amp;#236;nh th&amp;#236; go.sum s&amp;#7869; &amp;#273;&amp;#432;&amp;#7907;c t&amp;#7841;o ra, l&amp;#432;u v&amp;#7871;t version c&amp;#7911;a c&amp;#225;c module s&amp;#7917; d&amp;#7909;ng trong project.&lt;/p&gt;
&lt;p dir=&quot;ltr&quot;&gt;N&amp;#7897;i dung trong file go.sum&lt;/p&gt;
&lt;pre class=&quot;language-go&quot;&gt;&lt;code&gt;github.com/gorilla/mux v1.7.3 h1:gnP5JzjVOuiZD07fKKToCAOjS0yOpj/qPETTXCCS6hw=

github.com/gorilla/mux v1.7.3/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=&lt;/code&gt;&lt;/pre&gt;
&lt;p dir=&quot;ltr&quot;&gt;Sau khi &amp;#7913;ng d&amp;#7909;ng &amp;#273;&amp;#227; ch&amp;#7841;y, anh em c&amp;#243; th&amp;#7875; tham kh&amp;#7843;o b&amp;#224;i vi&amp;#7871;t n&amp;#224;y&amp;#160;&lt;span style=&quot;color: #3366ff;&quot;&gt;https://anhlamweb.com/bai-viet-70/xay-dung-rest-api-co-ban-trong-golang.html&lt;/span&gt;&lt;span style=&quot;color: #3366ff;&quot;&gt;&amp;#160;&lt;/span&gt;&amp;#273;&amp;#7875; test l&amp;#7841;i c&amp;#225;c API nh&amp;#233;. Ch&amp;#250;c anh em th&amp;#224;nh c&amp;#244;ng.&lt;/p&gt;
&lt;/body&gt;
&lt;/html&gt;

Để quản lý các modules trong Go một cách tiện lợi và dễ dàng hơn, từ phiên bản Go 1.11 đội ngũ Go đã cho ra mắt Go Modules. Chúng ta có thể sử dụng Go Modules, gọi tắt là Go Mod để install các gói module một cách tự động khi chúng ta thực hiện thực thi chương trình

Cách Sử Dụng Go Modules

<!DOCTYPE html>
<html>
<head>
</head>
<body>
<div class="mce-toc">
<h2>Mục lục:</h2>
<ul>
<li><a href="#mcetoc_1dj9vng0kv">Biến v&agrave; gi&aacute; trị trong Golang</a></li>
<li><a href="#mcetoc_1dj9vng0k10">Hằng số trong Golang</a></li>
<li><a href="#mcetoc_1dj9vng0k11">V&ograve;ng lặp For trong Golang</a></li>
<li><a href="#mcetoc_1dj9vng0k12">C&acirc;u lệnh điều khiển If/Else trong Golang</a></li>
<li><a href="#mcetoc_1dj9vng0k13">Switch Case trong Golang</a></li>
<li><a href="#mcetoc_1dj9vng0k14">H&agrave;m (Functions)&nbsp;trong Golang</a></li>
<li><a href="#mcetoc_1dj9vng0k15">H&agrave;m trả về nhiều gi&aacute; trị (Multiple Return Values) trong Golang.</a></li>
<li><a href="#mcetoc_1dj9vng0k16">H&agrave;m bất định (Variadict Function) trong Golang.</a></li>
</ul>
</div>
<h2 id="mcetoc_1dj9vng0kv" dir="ltr">Biến v&agrave; gi&aacute; trị trong Golang</h2>
C&aacute;c biến (variables) trong Go phải được x&aacute;c định v&agrave; định nghĩa r&otilde; r&agrave;ng.
Từ kh&oacute;a &ldquo;var&rdquo; trong Go d&ugrave;ng để khai b&aacute;o một hoặc nhiều biến, v&agrave; khi khai b&aacute;o biến phải c&oacute; t&ecirc;n biến v&agrave; kiểu dữ liệu của biến một c&aacute;ch r&otilde; r&agrave;ng.
C&oacute; c&aacute;c kiểu khai b&aacute;o biến v&agrave; g&aacute;n gi&aacute; trị như sau:
<pre class="language-go"><code>package main
 
import "fmt"
 
func main(){
 //var [t&ecirc;n biến] = [gi&aacute; trị]
 var a = true
 fmt.Printf("a=%t\n", a)
 //[t&ecirc;n biến] := [gi&aacute; trị]
 b := "good bye"
 fmt.Printf("b=%s\n", b)
 //var [t&ecirc;n biến 1], [t&ecirc;n biến 2] [kiểu gi&aacute; trị] = [gi&aacute; trị]
 var c, d int = 1 ,2
 fmt.Printf("c=%d\nd=%d\n", c, d)
 //var [t&ecirc;n biến] [kiểu gi&aacute; trị]
 //[t&ecirc;n biến] = [gi&aacute; trị]
 var e float32
 e = 10.5
 fmt.Printf("e=%f\n",e)
 fmt.Scanf("Pause")
}
</code></pre>
Output: (<a style="color: #3366ff;" href="https://play.golang.org/p/aXqrisIra1J" target="_blank" rel="noopener">Run Code</a>)
<pre class="language-go"><code>a=true
b=good bye
c=1
d=2
e=10.500000</code></pre>
<h2 id="mcetoc_1dj9vng0k10" dir="ltr">Hằng số trong Golang</h2>
Hằng số l&agrave; một gi&aacute; trị cố định v&agrave; kh&ocirc;ng thay đổi. Cũng như c&aacute;c ng&ocirc;n ngữ lập tr&igrave;nh kh&aacute;c để khai b&aacute;o hằng số trong Go ch&uacute;ng ta sử dụng từ kh&oacute;a const. Go hỗ trợ hằng số cho k&yacute; tự (character), chuỗi (string), kiểu bool (boolean), v&agrave; c&aacute;c gi&aacute; trị số (numeric values).
Từ kh&oacute;a const c&oacute; thể khai b&aacute;o ở bất cứ đ&acirc;u m&agrave; từ kh&oacute;a var c&oacute; thể.
<pre class="language-go"><code>package main
 
import "fmt"
 
const hello string = "Hello World"
 
func main(){
 fmt.Printf("hello=%s\n", hello)
 const n = 100
 nx2 := n*2
 fmt.Printf("n=%d\n", n)
 fmt.Printf("nx2=%d\n", nx2)
 fmt.Scanf("Pause")
}
</code></pre>
Output (<a style="color: #3366ff;" href="https://play.golang.org/p/w3jYQEys0Vu" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>hello=Hello World
n=100
nx2=200</code></pre>
<h2 id="mcetoc_1dj9vng0k11" dir="ltr">V&ograve;ng lặp For trong Golang</h2>
Go cũng c&oacute; v&ograve;ng lặp For nhưng kh&ocirc;ng c&oacute; v&ograve;ng lặp While, ch&uacute;ng ta c&oacute; thể sử dụng c&uacute; ph&aacute;p của v&ograve;ng lặp For để thay thế cho While.
<pre class="language-go"><code>package main
 
import "fmt"
 
func main(){
 fmt.Println("Go does not have While loop we should use For instead:")
 i:=5
 for i &gt; 0{
 fmt.Printf("%d\t",i)
 i--
 }
 fmt.Println("\nBreak out of the loop:")
 for {
 fmt.Printf("loop \t")
 break
 }
 fmt.Println("\nContinue to the next iteration of the loop:")
 for n := 0; n &lt;= 5; n++ {
 if n%2 == 0 {
 continue
 }
 fmt.Printf("%d\t",n)
 }
 fmt.Scanf("Pause")
}</code></pre>
Output (<a style="color: #3366ff;" href="https://play.golang.org/p/TmyK8bIdmHU" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>Go does not have While loop we should use for instead:
5 4 3 2 1
Break out of the loop:
loop
Continue to the next iteration of the loop:

1 3 5</code></pre>
<h2 id="mcetoc_1dj9vng0k12" dir="ltr">C&acirc;u lệnh điều khiển If/Else trong Golang</h2>
If/Else trong Golang c&oacute; 1 điểm đặc biệt l&agrave; c&oacute; th&ecirc;m sự ngắn gọn, ch&uacute;ng ta c&oacute; thể g&aacute;n gi&aacute; trị hoặc lấy gi&aacute; trị từ một h&agrave;m n&agrave;o đ&oacute; tr&ecirc;n c&uacute; ph&aacute;p của lệnh If.
<pre class="language-go"><code>package main

import (
	"bufio"
	"fmt"
	"math/rand"
	"os"
)

var (
	PASSWORD = "123456"
)

func getRandNumber(n int) int {
	return rand.Intn(n)
}

func main() {
	var password string

	scanner := bufio.NewScanner(os.Stdin)

	fmt.Print("Enter your password:")
	for scanner.Scan() {
		password = scanner.Text()
		break
	}
	
	if password == PASSWORD {
		fmt.Printf("Your password is correct\n")
	} else {
		fmt.Printf("Your password is incorrect\n")
	}

	//Call a function get assign value to num variable.
	if num := getRandNumber(20); num &lt; 19 {
		fmt.Printf("number %d is smaller than 19\n", num)
	}

	if num := getRandNumber(20); num &gt; 10 {
		fmt.Printf("number %d is greater than 10", num)
	} else if num &lt; 10 {
		fmt.Printf("number %d is smaller than 10", num)
	} else {
		fmt.Printf("number %d is equal to 10", num)
	}
	fmt.Scanf("Pause")
}
</code></pre>
Output (<a style="color: #3366ff;" href="https://play.golang.org/p/YFu2-NFHoJ8" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>Enter your password:123456
Your password is correct
number 1 is smaller than 19
number 7 is smaller than 10</code></pre>
<h2 id="mcetoc_1dj9vng0k13" dir="ltr">Switch Case trong Golang</h2>
Ch&uacute;ng ta c&oacute; thể sử dụng nhiều điều kiện trong một case bằng dấu phẩy như v&iacute; dụ 1 b&ecirc;n dưới. V&agrave; ch&uacute;ng ta cũng c&oacute; thể sử dụng switch như c&acirc;u lệnh If/Else như v&iacute; dụ 2, v&agrave; cũng giống như c&acirc;u lệnh điều khiển If/Else Go cho ph&eacute;p ta g&aacute;n hoặc gọi h&agrave;m để g&aacute;n gi&aacute; trị cho biến tại switch, như v&iacute; dụ 3.
<pre class="language-go"><code>package main
 
import (
 "bufio"
 "fmt"
 "os"
)
 
func main() {
 var say string
 
 scanner := bufio.NewScanner(os.Stdin)
 
 fmt.Print("Say something:")
 for scanner.Scan() {
 say = scanner.Text()
 break
 }
 // 1. We can use commas for multiple expressions in the same case
 switch say {
 case "hello", "hi":
 fmt.Println("Greetings")
 case "good bye":
 fmt.Println("Bye")
 default:
 fmt.Println("Unknow")
 }
 
 // 2. Switch without an expression
 x := 10
 switch {
 case x &lt; 10:
 fmt.Println("x is smaller than 10")
 case x &gt; 10:
 fmt.Println("x is greater than 10")
 default:
 fmt.Println("x is equal to 10")
 }
 
 // 3. Assign a value in the expression of switch
 whatIsMyType := func(i interface{}) {
 switch t := i.(type) {
 case string:
 fmt.Println("You are a string")
 case int:
 fmt.Println("You are an integer value")
 default:
 fmt.Printf("Your are %T", t)
 }
 }
 
 whatIsMyType("Hello World")
 whatIsMyType(1000)
 whatIsMyType(true)
 
 fmt.Scanf("Pause")
}
</code></pre>
Output (<a style="color: #3366ff;" href="https://play.golang.org/p/_h0P9dFCzEl" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>Say something:hello
Greetings
x is equal to 10
You are a string
You are an integer value
Your are bool</code></pre>
<h2 id="mcetoc_1dj9vng0k14" dir="ltr">H&agrave;m (Functions)&nbsp;trong Golang</h2>
Để khai b&aacute;o một h&agrave;m ta d&ugrave;ng từ kh&oacute;a &ldquo;func&rdquo;.
C&aacute;ch 1: H&agrave;m với gi&aacute; trị trả về
func [t&ecirc;n H&agrave;m]([t&ecirc;n biến 1] [kiểu biến], [t&ecirc;n biến 2] [kiểu biến]) [kiểu trả về]{
&nbsp; &nbsp; &nbsp;//th&acirc;n h&agrave;m...
}
C&aacute;ch 2: H&agrave;m r&uacute;t gọn kiểu biến nếu c&aacute;c kiểu của biến đều c&ugrave;ng chung kiểu
func [t&ecirc;n H&agrave;m]([t&ecirc;n biến 1],&nbsp; [t&ecirc;n biến 2] [kiểu biến]) [kiểu trả về]{
&nbsp; &nbsp; &nbsp;//th&acirc;n h&agrave;m...
}
<span style="font-size: 12pt; font-family: Georgia; color: #261a3b; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">&nbsp;
<pre class="language-go"><code>package main

import "fmt"

//Chu vi h&igrave;nh chữ nhật
//Rectangle Perimeter
//C&aacute;ch khai b&aacute;o 1
func rectPerimeter(a int, b int) int {
	return (a + b) * 2
}

//Diện t&iacute;ch h&igrave;nh chữ nhật
//Rectangle Area
//C&aacute;ch khai b&aacute;o 2
func rectArea(a, b int) int {
	return a * b
}

func main() {
	a := 2
	b := 3
	rectPeri := rectPerimeter(a, b)
	fmt.Printf("Perimeter of rectangle is %d\n", rectPeri)
	rectAr := rectArea(a, b)
	fmt.Printf("Area of rectangle is %d\n", rectAr)
	fmt.Scanf("Pause")
}
</code></pre>
Output(<a style="color: #3366ff;" href="https://play.golang.org/p/kM2BFhNgFeo" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>Perimeter of rectangle is 10
Area of rectangle is 6</code></pre>
&nbsp;
<h2 id="mcetoc_1dj9vng0k15" dir="ltr">H&agrave;m trả về nhiều gi&aacute; trị (Multiple Return Values) trong Golang.</h2>
H&agrave;m trả về nhiều gi&aacute; trị trong Golang c&oacute; c&aacute;c c&aacute;ch viết sau
C&aacute;ch 1: H&agrave;m với gi&aacute; trị trả về
func [t&ecirc;n H&agrave;m]([t&ecirc;n biến 1] , [t&ecirc;n biến 2] [kiểu biến]) ([kiểu trả về 1], [kiểu trả về 2]){
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //th&acirc;n h&agrave;m&hellip;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;//logic t&iacute;nh to&aacute;n...
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return [gi&aacute; trị trả về 1], [gi&aacute; trị trả về 2]
}
C&aacute;ch 2: H&agrave;m khai b&agrave;o trước t&ecirc;n của gi&aacute; trị trả về, nếu đ&atilde; khai b&aacute;o trước gi&aacute; trị trả về th&igrave; chỉ cần c&oacute; return m&agrave; kh&ocirc;ng cần phải bỏ c&aacute;c gi&aacute; trị b&ecirc;n cạnh từ kh&oacute;a return
func [t&ecirc;n H&agrave;m]([t&ecirc;n biến truyền v&agrave;o 1] , [t&ecirc;n biến truyền v&agrave;o 2] [kiểu biến truyền v&agrave;o]) ([t&ecirc;n biến trả về 1] [kiểu trả về 1], [t&ecirc;n biến trả về 2][kiểu trả về 2]){
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;//th&acirc;n h&agrave;m&hellip;
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //logic t&iacute;nh to&aacute;n...
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return
}
C&aacute;ch 3: H&agrave;m khai b&aacute;o trước t&ecirc;n gi&aacute; trị trả về với c&aacute;ch viết r&uacute;t gọn kiểu trả về nếu tất cả c&aacute;c gi&aacute; trị trả về c&ugrave;ng kiểu.
func [t&ecirc;n H&agrave;m]([t&ecirc;n biến truyền v&agrave;o 1] , [t&ecirc;n biến truyền v&agrave;o 2] [kiểu biến truyền v&agrave;o]) ([t&ecirc;n biến trả về 1],&nbsp; [t&ecirc;n biến trả về 2][kiểu trả về]){
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; //th&acirc;n h&agrave;m&hellip;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;//logic t&iacute;nh to&aacute;n...
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return
}
<pre class="language-go"><code>package main

import "fmt"

//Chu vi h&igrave;nh chữ nhật
//Rectangle Perimeter
func rectPerimeter(a int, b int) int {
	return (a + b) * 2
}

//Diện t&iacute;ch h&igrave;nh chữ nhật
//Rectangle Area
func rectArea(a, b int) int {
	return a * b
}

//Chu vi v&agrave; diện t&iacute;ch h&igrave;nh chữ nhật c&aacute;ch 1
func rectPeriAndArea1(a, b int) (int, int) {
	rectPeri := rectPerimeter(a, b)
	rectArea := rectArea(a, b)
	return rectPeri, rectArea
}

//Chu vi v&agrave; diện t&iacute;ch h&igrave;nh chữ nhật c&aacute;ch 2
func rectPeriAndArea2(a, b int) (rectPeri int, rectAr int) {
	rectPeri = rectPerimeter(a, b)
	rectAr = rectArea(a, b)
	return
}

//Chu vi v&agrave; diện t&iacute;ch h&igrave;nh chữ nhật c&aacute;ch 3
func rectPeriAndArea3(a, b int) (rectPeri, rectAr int) {
	rectPeri = rectPerimeter(a, b)
	rectAr = rectArea(a, b)
	return
}

func main() {
	a := 2
	b := 3
	rectPeri1, rectAr1 := rectPeriAndArea1(a, b)
	fmt.Printf("rectPeri1=%d, rectAr1=%d\n", rectPeri1, rectAr1)
	rectPeri2, rectAr2 := rectPeriAndArea2(a, b)
	fmt.Printf("rectPeri2=%d, rectAr2=%d\n", rectPeri2, rectAr2)
	rectPeri3, rectAr3 := rectPeriAndArea3(a, b)
	fmt.Printf("rectPeri3=%d, rectAr3=%d\n", rectPeri3, rectAr3)
	fmt.Scanf("Pause")
}
</code></pre>
Output(<a style="color: #3366ff;" href="https://play.golang.org/p/Nl-dMLPtKx2" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>rectPeri1=10, rectAr1=6
rectPeri2=10, rectAr2=6
rectPeri3=10, rectAr3=6
</code></pre>
<h2 id="mcetoc_1dj9vng0k16" dir="ltr">H&agrave;m bất định (Variadict Function) trong Golang.</h2>
H&agrave;m bất định (Variadict Function) l&agrave; một h&agrave;m chấp nhận số lượng đối số kh&aacute;c nhau v&agrave; kh&ocirc;ng biết trước.&nbsp;
Ch&uacute;ng ta c&oacute; thể thấy c&oacute; dấu ... ngộ ha. Nhưng n&oacute; c&oacute; &yacute; nghĩa để khai b&aacute;o số phần tử kh&ocirc;ng biết trước của đối số truyền v&agrave;o h&agrave;m.
H&agrave;m n&agrave;y cũng nhận gi&aacute; trị l&agrave; một array nhưng sau array n&agrave;y lại c&oacute; dấu ... vậy n&oacute; c&oacute; &yacute; nghĩa l&agrave; g&igrave; nhỉ? Dấu ... n&agrave;y sẽ tự động ph&acirc;n t&aacute;ch c&aacute;c phần tử tr&ograve;ng mảng th&agrave;nh c&aacute;c đối số v&agrave;o h&agrave;m.
V&iacute; dụ:
myArray&nbsp; &nbsp; = [1,2,3,4]
myArray... = 1,2,3,4
<pre class="language-go"><code>package main

import "fmt"

func min(numbers ...int) int {
	result := numbers[0]
	for _, num := range numbers {
		if result &gt; num {
			result = num
		}
	}
	return result
}

func main() {
	fmt.Printf("min of 5,3,2 is %d\n", min(5, 3, 2))
	fmt.Printf("min of 5,3,2,1 is %d\n", min(5, 3, 2, 1))
	numbers := []int{5, 3, 2, 1, 0}
	fmt.Printf("min of array [5,3,2,1,0] is %d", min(numbers...))
	fmt.Scanf("Pause")
}
</code></pre>
Output(<a style="color: #3366ff;" href="https://play.golang.org/p/mDSlfzYPwCp" target="_blank" rel="noopener">Run Code</a>):
<pre class="language-go"><code>min of 5,3,2 is 2
min of 5,3,2,1 is 1
min of array [5,3,2,1,0] is 0</code></pre>
</body>
</html>

Cũng như các ngôn ngữ lập trình khác Golang cũng có các thành phần cơ bản như biến, hằng, vòng lặp, câu lệnh rẽ nhánh, mảng, con trỏ ..v..v.

hoc golang tu con so 0 - phan 2 cac thanh phan co ban trong go

Học Golang từ con số 0 - Phần 2 Các Thành Phần Cơ Bản Trong Go

<!DOCTYPE html>
<html>
<head>
</head>
<body>
<div class="mce-toc">
<h2>Mục lục:</h2>
<ul>
<li><a href="#mcetoc_1dj9vkpo8i">Mở đầu</a></li>
<li><a href="#mcetoc_1dj9vkpo8j">C&agrave;i đặt Golang tr&ecirc;n Windows.</a>
<ul>
<li><a href="#mcetoc_1dj9vkpo8k">C&agrave;i đặt</a></li>
<li><a href="#mcetoc_1dj9vkpo8l">Thiết lập biến m&ocirc;i trường.</a></li>
</ul>
</li>
<li><a href="#mcetoc_1dj9vkpo8m">C&agrave;i đặt Golang tr&ecirc;n Ubuntu.</a></li>
<li><a href="#mcetoc_1dj9vkpo8n">Hello world trong Golang.</a></li>
<li><a href="#mcetoc_1dj9vkpo8p">T&oacute;m Lại:</a></li>
</ul>
</div>
<h2 id="mcetoc_1dj9vkpo8i" dir="ltr">Mở đầu</h2>
Để biết Golang l&agrave;m được những g&igrave; v&agrave; n&oacute; lợi hại như thế n&agrave;o th&igrave; m&igrave;nh h&atilde;y bắt tay v&agrave;o việc c&agrave;i đặt Go l&ecirc;n m&aacute;y v&agrave; thực h&agrave;nh th&ocirc;i n&agrave;o.
Nếu c&aacute;c bạn th&iacute;ch đọc hướng dẫn v&agrave; t&agrave;i liệu bằng tiếng anh v&agrave; v&iacute; dụ cụ thể th&igrave; c&oacute; thể tham khảo c&aacute;c nguồn sau đ&acirc;y m&igrave;nh cũng học v&agrave; tham khảo tr&ecirc;n c&aacute;c trang n&agrave;y:
Go by example: <a style="color: #3366ff;" href="https://gobyexample.com/">https://gobyexample.com/</a>
The Tour of Go:&nbsp; <a style="color: #3366ff;" href="https://tour.golang.org">https://tour.golang.org</a>
How To Write Go Code: <a style="color: #3366ff;" href="https://golang.org/doc/code.html">https://golang.org/doc/code.html</a>
Để download g&oacute;i c&agrave;i đặt c&aacute;c bạn v&agrave;o trang n&agrave;y để lấy g&oacute;i ph&ugrave; hợp với m&aacute;y c&aacute;c bạn: <a style="color: #3366ff;" href="https://golang.org/dl/">https://golang.org/dl/</a>
<h2 id="mcetoc_1dj9vkpo8j">C&agrave;i đặt Golang tr&ecirc;n Windows.</h2>
<h3 id="mcetoc_1dj9vkpo8k" dir="ltr">C&agrave;i đặt</h3>
C&aacute;c bạn v&agrave;o trang download của Golang m&igrave;nh đ&atilde; để link ph&iacute;a tr&ecirc;n v&agrave; t&iacute;m đến chỗ dowload g&oacute;i c&agrave;i đặt cho Microsoft Windows, tiến h&agrave;nh download về th&ocirc;i.
<img style="display: block; margin-left: auto; margin-right: auto;" src="https://lh3.googleusercontent.com/48oEitXGF0zUeJDJBjmrExnM2A738wwCdwQGJxs5xs0tJncgt93d1VQiXTEiyJasaC5Qcyyjgv4Kns84i7bQvqbtd13f7_136e01iFOOq20_rDvUKLAwT1NNlhhI9iK98tPFbRg7" width="624" height="164" />
Cũng như c&agrave;i đặt c&aacute;c chương tr&igrave;nh kh&aacute;c c&aacute;c bạn nếu kh&ocirc;ng muốn điều chỉnh g&igrave; th&igrave; cứ nhấn Next, next nh&eacute;.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh4.googleusercontent.com/VMKWrXTyZMeuWCHwHLqc5QVrEd1SDGnoMLXde84UjZa4DwqdMFsZxwXPydy1N6tPVAkc3KK-KxIt0pgWOuKpM9T9xHw6k_QGsY_6SmubJtsPio0jP1SeKj7onmfsljX9B4N6lPOt" width="490" height="383" />
Chấp nhận điều khoản, nhấn Next.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh5.googleusercontent.com/Ce3yEjoQBwQnX2jLvs7iKuXIVaprvKOI03LHvn4HhYnyicaKQ5XXQQHN7nLS-rhMlsxwLX2YJLZg4ks_jG1tow_MKj8rH7OKuH_7f9A6uktqnHACSbMYTknkFIgsl_DsuBh7tcny" width="488" height="381" />
Ở bước n&agrave;y c&aacute;c bạn c&oacute; thể điều chỉnh lại đường dẫn m&agrave; ch&uacute;ng ta muốn c&agrave;i đặt Golang tr&ecirc;n m&aacute;y, sau đ&oacute; nhấn Next.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh3.googleusercontent.com/w3LJKOPonMQAkPrerxqmyoMs3rEY-MPhG2MIvY_aSbrDXxTPYNU-vAu1pn7SNCYtv7ilGHiwtlMDF9GkpWgywe4DOXxBkFg4waPLpkM_-PxLn7iqFFOpdQ7_ZYyjCaa-USs_4Qka" width="489" height="380" />
Nhấn Install n&agrave;o hỏi nhiều qu&aacute; đấy.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh3.googleusercontent.com/nU8ZCEPDHv47JKMswIqzekRMiOomfpbLQz-eBXNVMQaL7OzC4z4KJQ5o994o5PM2fPnCQr_cqKUYTLq_PC4su_pEXI3dCRVJrM1N3gMf5Ic1Cx8SQiOWZftMMy7HQsKvz47JE3tI" width="487" height="382" />
C&aacute;c bạn chờ trong gi&acirc;y l&aacute;t nh&eacute;, 1 x&iacute; nữa th&ocirc;i l&agrave; xong rồi.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh3.googleusercontent.com/OO_7JWWgk1WICCEzIWHStOL76Yl6eBZBuz2sXlLPfz_8G4f3taqAGDE9bMx8pNVp-NDdX7U7wzXyRyOzX4kEfkoIBgzwRiyit-lgftVkD-3wKlyTzOa0EeUmLCR2tTcpGXRlr-vE" width="485" height="380" />
Ok, nhấn Finish để ho&agrave;n th&agrave;nh việc c&agrave;i đặt.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh3.googleusercontent.com/Xl9XOym95GmWFr2dbO22L7MJcO4Zr8yCPD9UX1zwz8yQImbQpPOER1HLdjEFr500WKQxMipurW7o95eRTzQeHTuIAUg7N6xNxX4-0CTa3AimZrOLL5cj-GOYyZ14LD2w6F61PVS0" width="493" height="381" />
Như vậy ch&uacute;ng ta đ&atilde; ho&agrave;n tất cả c&aacute;c bước c&agrave;i đặt, bước tiếp theo l&agrave; setup biến m&ocirc;i trường GOROOT v&agrave; GOPATH.
<h3 id="mcetoc_1dj9vkpo8l">Thiết lập biến m&ocirc;i trường.</h3>
C&aacute;c bạn nhấn n&uacute;t Windows v&agrave; g&otilde; t&igrave;m đến c&agrave;i đặt biến m&ocirc;i trường như h&igrave;nh b&ecirc;n dưới.
<code><img style="display: block; margin-left: auto; margin-right: auto; max-width: 300px;" src="https://lh3.googleusercontent.com/EQgtw9t5p8drwq9mGJtUug23k2lh9tzoSZwhWZQnF9mKveXCPo9KNqjIzhq0PIh2R4NXj1YnnXLJqMrEvRBSZOrxR2IsE5xV4eWrnLtFQ27iAE4ZXImefLgpC4xOUa7g4wzam1vy" width="300" height="525" /></code>
Chọn v&agrave;o Environment Variables.
<img style="max-width: 480px; display: block; margin-left: auto; margin-right: auto;" src="https://lh4.googleusercontent.com/3QXmE4gKdXuVmSpUyxb5EePBJnlcFrMX7RWcsVeU5D878ox5Hzy7cypoSAfMZfAZX11pn2pwv8bkpWnG0Ypx8nQI-NdyD5YTQVfMgaJIkZHxCVsibD5ctnNdrv-Tv47AVgJMFRtM" width="381" height="547" />
Sau đ&oacute; chọn New v&agrave; th&ecirc;m một biến (variable) t&ecirc;n l&agrave; GOPATH với đường dẫn đến thư mục ch&uacute;ng ta muốn tạo c&aacute;c project Golang, đ&acirc;y l&agrave; nơi l&agrave;m việc với code Go của ch&uacute;ng ta.
<img style="max-width: 483px; display: block; margin-left: auto; margin-right: auto;" src="https://lh4.googleusercontent.com/7uBMG7fqYhb37sq0jpFWtr04G04wrIq3DT0u_jHwcYPaEHddZ8C5PnQvugTMEy_vCFtuIUHwIS0RFIKxxESBzBcwZQuJWudqcyZMxk1zou-mTB52m_Agml_kVgMsDiPggcohvDLB" width="323" height="456" />
V&agrave; nh&igrave;n xuống biến c&oacute; t&ecirc;n Path để xem đ&atilde; dẫn tới thư mục bin của Go m&agrave; ban đầu ch&uacute;ng ta đ&atilde; c&agrave;i đặt chưa nh&eacute;.
<img style="max-width: 490px; display: block; margin-left: auto; margin-right: auto;" src="https://lh5.googleusercontent.com/nff5ZUsISqMChtyIT0umRGY3bwFnoDyEnlLbNtIaN2n-7hJ3XtjZVmGaEhJPbxJVaH2rULKBaHQOuSV7bxL_0zxsHlRqtpl1R_bUJ0hiW0szeLv7QdU19WAVlt_-EApdo-2k25ce" width="340" height="415" />
M&igrave;nh thấy n&oacute; đ&atilde; c&oacute; rồi n&ecirc;n l&agrave; ok, nếu chưa c&oacute; th&igrave; m&igrave;nh sẽ th&ecirc;m v&agrave;o.
<img style="max-width: 501px; display: block; margin-left: auto; margin-right: auto;" src="https://lh3.googleusercontent.com/2RMlVHMIN7ZQcBVXX5RkN9FJeMssZzNtSX5Gk6uI9HRAreZWLu_veyKuIebnyVgS_mDa2hjDUwqDc569BHnzIUKABNCberFdRk41RJi2JtO1C-4_i8Cuz520VFVWcRAerPPcfoBL" width="355" height="419" />
Sau đ&oacute; restart lại m&aacute;y v&agrave; kiểm tra Go đ&atilde; được setup đ&uacute;ng chưa.
Kiểm tra version của Go bằng command go version
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 631px;" src="https://lh4.googleusercontent.com/Blpa_ef0YI91k0PmTZ5jg-vAoBEL62zY9jUzi8RCW3wlfht74IkWJRtWMxsaLwvUFUqqOhIpBk2VSJd3JkHbcTfUC3wVbjEsDLiDYspihffGlevkMcR6u65fccv0O3AKNIfUGFE5" width="631" height="402" />
Kiểm tra cấu h&igrave;nh c&agrave;i đặt biến m&ocirc;i trường lưu &yacute; 2 biến l&agrave; GOROOT v&agrave; GOPATH.
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh6.googleusercontent.com/HkAYOaSjVGghdxdEcDqA27L1CUcKSwjQ5IZvt_w88Okq_zqIwGcUpOGxlipJftd_7JYbwqJi60jAsrCi_o8bLz1VX2Oqh84lxq9hM0gbIh4eBjig8emApA_5mNB8btVp_ybwIEhS" width="624" height="463" />
<h2 id="mcetoc_1dj9vkpo8m">C&agrave;i đặt Golang tr&ecirc;n Ubuntu.</h2>
Truy cập v&agrave;o m&aacute;y Ubuntu thực hiện việc update apt.&nbsp;
<code>sudo apt-get update</code>
<code>sudo apt-get -y upgrade</code>
Tải Golang về m&aacute;y.&nbsp;
V&agrave;o thư mục m&agrave; ch&uacute;ng ta muốn ở đ&acirc;y m&igrave;nh sẽ bỏ v&agrave;o thư mục /home/vxphong/go v&agrave; thư mục n&agrave;y m&igrave;nh đ&atilde; tạo sẵn tr&ecirc;n m&aacute;y.
<code>cd /home/vxphong/go</code>
<code>wget <a href="https://dl.google.com/go/go1.12.7.linux-amd64.tar.gz">https://dl.google.com/go/go1.12.7.linux-amd64.tar.gz</a></code>
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh5.googleusercontent.com/Z33yoofwY6EsYVgpyHYd-izhON5tjtr_TdsCVVMeWGorKOs-YNGcJj7Y8fvoyImTfoiXRQH4TTsQmIueJS8KlthuE7nNPioE-su-3WPBv3QbOOJ4VcCaxHx5aH34vu4mwnFl2e8n" width="624" height="417" />
Sau khi đ&atilde; tải được g&oacute;i c&agrave;i đặt xuống ta tiến h&agrave;nh giải n&eacute;n (extract).
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh5.googleusercontent.com/3MnQalQ5lal6MgkpVH7aBvgr6FWK--iv-vcVHsJKqNogs0R85c9Umadf8u4slTHD6EQHwwCxGZiCmEl6FeiIB_tJBkAjONABmhxbubgFgWn0o9w0yxUmy-pQLyAVo80fEmhpZq-Q" width="624" height="413" />
Ở đ&acirc;y m&igrave;nh c&aacute;i nhiều phi&ecirc;n bản n&ecirc;n m&igrave;nh sẽ đổi t&ecirc;n thư mục go vừa extract ra th&agrave;nh số version nha.
<code>mv go 1.12.7</code>
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh4.googleusercontent.com/6MV7tTWybYpjbLVdWA15_fLrA8CEALRbrnt_hSkwog_fEZ5TTdzFuwLhRFwr1DHpDTrFdbiIMTGJENTXBD3xVaHNFrfLKZTkCVnhoGTlR9-wlZZLwKW5RJB0NJmRjNrGinc9V78i" width="624" height="416" />
Để gọn tr&ocirc;ng nh&igrave;n sạch hơn m&igrave;nh x&oacute;a lu&ocirc;n file tar.gz nha, v&agrave; đ&acirc;y l&agrave; thư mục m&agrave; m&igrave;nh đ&atilde; c&agrave;i đặt Go.
<code>cd 1.12.7</code>
<code>pwd</code>
Ch&uacute;ng ta sẽ nhớ đường dẫn n&agrave;y để t&iacute; nữa c&agrave;i đặt biến m&ocirc;i trường GOROOT nha.
/home/vxphong/go/1.12.7
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh3.googleusercontent.com/52AC7hyia39pav-d5UX2faicP0-HubB0RVaUqbAqpLD-u88ksNHmHLcD-mYWXOIVJgvJDQWBJ6h3k1MXjJkfN05ODSFHgVeg0sQ_a8hn15C67zCu7ekuhU1P8tIrAkIgoRyG6zTW" width="624" height="413" />
Tạo ra thư mục l&agrave;m việc với code Go
<code>mkdir /home/vxphong/gopath</code>
Tiếp theo ch&uacute;ng ta h&atilde;y thiết&nbsp; lập GOPATH v&agrave; GOROOT
<code>nano /home/vxphong/.bashrc</code>
V&agrave; export c&aacute;c đường dẫn để thiết lập biến m&ocirc;i trường GOPATH, GOROOT v&agrave; PATH.
<code>export GOROOT=/home/vxphong/go/1.12.7</code>
<code>export GOPATH=/home/vxphong/gopath</code>
<code>export PATH=$PATH:$GOROOT/bin:$GOPATH/bin</code>
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh3.googleusercontent.com/RWCu9-Mj44NTWExPFBjdptAeOikcQ4tCVWxKJJzKsKj2MN_leOIjieG6lqg1Zqhv53MRSy8YF0vXe5grfysBDKqcqho-b_fMsvBnnOoXwAtJGLVFai0xZ-ylBiUK_fSDfSlE9vMn" width="624" height="408" />
Như vậy l&agrave; đ&atilde; xong kiểm tra version của Go n&agrave;o c&aacute;c bạn, ch&uacute;ng ta tắt terminal đang l&agrave;m việc đi v&agrave; mở lại.
<code>go version</code>
Kiểm tra c&aacute;c biến m&ocirc;i trường đ&atilde; thiết lập trước đ&oacute;.
<code>go env</code>
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh5.googleusercontent.com/ToXvZIfYpH1eOM-o0iSrNu_hAs0OZPZFHdjSlOGccRgTcbrVcfkHJss3dpAnBBVwzWHeHv3oq82fT0GfbHyJ7GK8s2LmnfmELNPkS_rwWZTcg8LPxN4DJylRot605RBBAcqKDjlT" width="624" height="412" />
<h2 id="mcetoc_1dj9vkpo8n">Hello world trong Golang.</h2>
Quay trở lại với m&aacute;y Windows của m&igrave;nh, c&aacute;c bạn nhớ l&uacute;c trước m&igrave;nh đ&aacute; thiết lập biến m&ocirc;i trường GOPATH kh&ocirc;ng? Trong thư mục GOPATH th&igrave; ch&uacute;ng ta tạo th&ecirc;m thư mục src nữa nha. nơi l&agrave;m việc để tạo ra c&aacute;c project sẽ nằm ở đ&oacute;.
<code>mkdir src</code>
<code>cd src</code>
<code>mkdir hello-world</code>
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 580px;" src="https://lh4.googleusercontent.com/3k1a_PLPLjbsN1jdeJtZ9Tg11PjbL9hlnmMAQ5sp_btWRWE8D5s3UKvXtvYjgqZior1IyWalBnsucObMfuQ5DzbX-O7zl4rpilspU0Z_R5p8ntphFXN6g-okLtkU6vAY6AXiou1D" width="580" height="368" />
Tạo file main.go trong thư mục hello-world với nội dung sau:
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 624px;" src="https://lh6.googleusercontent.com/v16DChGMRSBpBErACvY1mNVvZIZyU22xgAn2FE14K3STI4yP1eLImn_KhOp1wMgohJLjRG7cfoMyl7Y8aw1axms8wOaLjda62hj7soW9ycv_jB52W1MTvMFBqwrUXwPTsoAOd2Y6" width="624" height="264" /> 
<pre class="language-go"><code>package main

import "fmt"

func main(){
	fmt.Println("Hello World")
}</code></pre>
B&acirc;y giờ ch&uacute;ng ta tiến h&agrave;nh code v&agrave; chạy chương tr&igrave;nh Hello-World th&ocirc;i n&agrave;o
D&ugrave;ng c&acirc;u lệnh sau đ&acirc;y để chạy chương tr&igrave;nh.
<code>go run main.go</code>
<img style="display: block; margin-left: auto; margin-right: auto; max-width: 451px;" src="https://lh4.googleusercontent.com/uQKgrDQRPBOQabbBzchz1mY9FG25XzhDncgcQWqH2v_yBpXWNvNc-R5ufaLid4v4ZEZcIqJLq9vDF410_RbJTxyMKMzXbvRb_dBeGM4fj8HbChIStPXHZAWpqdqh8-Bn2Y28LZlU" width="451" height="197" />
<h2 id="mcetoc_1dj9vkpo8p" dir="ltr">T&oacute;m Lại:</h2>
Thư mục l&agrave;m việc sẽ nằm trong thư mục src nằm ở đường dẫn GOPATH do ch&uacute;ng ta đ&atilde; c&agrave;i đặt trước đ&oacute;. C&aacute;c bạn c&oacute; thấy c&aacute;c thư mục như github.com, golang.org kh&ocirc;ng đ&oacute; l&agrave; nơi chứa c&aacute;c thư viện m&agrave; ch&uacute;ng ta sẽ c&agrave;i đặt để sử dụng cho project. C&oacute; thể những b&agrave;i tiếp theo m&igrave;nh sẽ hướng dẫn c&aacute;c bạn c&aacute;i thư viện như thế n&agrave;o nha, nhưng thật ra n&oacute; rất đơn giản th&ocirc;i &agrave; chỉ cần 1 c&acirc;u lệnh l&agrave; n&oacute; sẽ tự động c&agrave;i v&agrave; bỏ v&agrave;o trong c&aacute;c thư mục tương ứng, chỉ cần import để lấy ra sử dụng th&ocirc;i.
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Để biết Golang làm được những gì và nó lợi hại như thế nào thì mình hãy bắt tay vào việc cài đặt Go lên máy và thực hành thôi nào.

hoc golang tu con so 0 - phan 1 cai dat golang tren linux va windows

Anh làm web

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