<h2 style="text-align: justify;"><strong>C&aacute;c lệnh điều khiển rẽ nh&aacute;nh</strong></h2>
<h3 style="text-align: justify;"><strong>1. Mệnh đề if</strong></h3>
<p style="text-align: justify;"><span style="font-weight: 400;">D&ugrave;ng để đưa ra 2 lựa chọn v&agrave; hoặc nhiều hơn dựa theo c&aacute;c điều kiện kh&aacute;c nhau</span></p>
<pre class="language-c" data-content="%23include%20%3Cstdio.h%3E%C2%A0%0A%0Aint%20main()%20%7B%0A%0A%C2%A0%C2%A0int%20age%20%3D%2021%3B%0A%0A%C2%A0%C2%A0if%20(age%20%3E%3D%2018)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22You%20can%20vote%22)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0A%C2%A0%C2%A0else%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22You%20cannot%20vote%22)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0Areturn%200%3B%0A%0A%7D" data-language="c" data-ace-language="c_cpp" data-name-language="C" data-main-file="main.c"><code>#include &lt;stdio.h&gt;

int main() {

  int age = 21;
  if (age &gt;= 18) {
    printf("You can vote");
  }
  else {
    printf("You cannot vote");
  }

return 0;
}</code></pre>
<h3 style="text-align: justify;"><strong>2. Lệnh lặp while </strong></h3>
<p style="text-align: justify;"><span style="font-weight: 400;">D&ugrave;ng để thực thi tập lệnh lặp đi lặp lại cho đến khi kh&ocirc;ng thoả m&atilde;n một biểu thức điều kiện</span></p>
<pre class="language-c" data-content="%23include%20%3Cstdio.h%3E%C2%A0%0A%0Aint%20main()%20%7B%0A%0A%C2%A0%C2%A0int%20age%3B%0A%0A%C2%A0%C2%A0printf(%22Guess%20the%20age%3A%20%22)%3B%0A%0A%C2%A0%C2%A0scanf(%22%25d%22%2C%20%26age)%3B%0A%0A%C2%A0%C2%A0while%20(age%20!%3D%2021)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22Your%20guess%20is%20wrong.%5Cn%22)%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22Guess%20the%20age%3A%20%22)%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0scanf(%22%25d%22%2C%20%26age)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0A%C2%A0%C2%A0printf(%22You%20guessed%20it%20right%22)%3B%0A%0A%C2%A0%C2%A0return%200%3B%0A%0A%7D" data-language="c" data-ace-language="c_cpp" data-name-language="C" data-main-file="main.c"><code>#include &lt;stdio.h&gt;

int main() {

  int age;
  printf("Guess the age: ");
  scanf("%d", &amp;age);
  while (age != 21) {
    printf("Your guess is wrong.\n");
    printf("Guess the age: ");
    scanf("%d", &amp;age);
  }
  printf("You guessed it right");

  return 0;
}</code></pre>
<h3 style="text-align: justify;"><strong>3. Lệnh lặp for </strong></h3>
<p style="text-align: justify;"><span style="font-weight: 400;">D&ugrave;ng để thực thi tập lệnh lặp lại một số lần nhất định dựa theo một biến cập nhật mỗi v&ograve;ng lặp</span></p>
<pre class="language-c" data-content="%23include%20%3Cstdio.h%3E%0A%0Aint%20main()%20%7B%0A%0A%C2%A0%C2%A0for%20(int%20i%20%3D%201%3B%20i%20%3C%3D%203%3B%20%2B%2Bi)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22%25d%5Cn%22%2C%20i)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0Areturn%200%3B%0A%0A%7D" data-language="c" data-ace-language="c_cpp" data-name-language="C" data-main-file="main.c"><code>#include &lt;stdio.h&gt;

int main() {

  for (int i = 1; i &lt;= 3; ++i) {
    printf("%d\n", i);
  }

return 0;
}</code></pre>
<h2 style="text-align: justify;"><strong>C&aacute;c mệnh đề kh&aacute;c</strong></h2>
<h3 style="text-align: justify;"><strong>1. Mệnh đề break</strong></h3>
<p style="text-align: justify;"><span style="font-weight: 400;">D&ugrave;ng để dừng v&ograve;ng lặp ngay lập tức, thường được d&ugrave;ng trong mệnh đề if.</span></p>
<pre class="language-c" data-content="%23include%20%3Cstdio.h%3E%0A%0Aint%20main()%20%7B%0A%0A%C2%A0%C2%A0for%20(int%20i%20%3D%201%3B%20i%20%3C%3D%20100%3B%20%2B%2Bi)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0if%20(i%20%3D%3D%203)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0break%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%7D%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22%25d%5Cn%22%2C%20i)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0Areturn%200%3B%0A%0A%7D" data-language="c" data-ace-language="c_cpp" data-name-language="C" data-main-file="main.c"><code>#include &lt;stdio.h&gt;

int main() {

  for (int i = 1; i &lt;= 100; ++i) {
    if (i == 3) {
      break;
    }
    printf("%d\n", i);
  }

return 0;
}</code></pre>
<h3 style="text-align: justify;"><strong>2. Mệnh đề continue</strong></h3>
<p style="text-align: justify;"><span style="font-weight: 400;">Bỏ qua c&aacute;c lệnh trong v&ograve;ng lặp đ&oacute; v&agrave; sang ngay v&ograve;ng lặp tiếp theo, thường được d&ugrave;ng trong mệnh đề if</span></p>
<pre class="language-c" data-content="%23include%20%3Cstdio.h%3E%0A%0Aint%20main()%20%7B%0A%0A%C2%A0%C2%A0for%20(int%20i%20%3D%201%3B%20i%20%3C%3D%205%3B%20%2B%2Bi)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0if%20(i%20%3D%3D%203%20%7C%7C%20i%20%3D%3D%204)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0continue%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%7D%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0printf(%22%25d%5Cn%22%2C%20i)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0Areturn%200%3B%0A%0A%7D" data-language="c" data-ace-language="c_cpp" data-name-language="C" data-main-file="main.c"><code>#include &lt;stdio.h&gt;

int main() {

  for (int i = 1; i &lt;= 5; ++i) {
    if (i == 3 || i == 4) {
      continue;
    }
    printf("%d\n", i);
  }

return 0;
}</code></pre>
<h3 style="text-align: justify;"><strong>3. Mệnh để switch</strong></h3>
<p style="text-align: justify;"><span style="font-weight: 400;">L&agrave; một phương &aacute;n thay thế cho mệnh đề if nếu cần đưa ra quyết định với nhiều lựa chọn.</span></p>
<pre class="language-c" data-content="%23include%20%3Cstdio.h%3E%0A%0Aint%20main()%20%7B%0A%0A%C2%A0%C2%A0int%20number%20%3D%203%3B%0A%0A%C2%A0%C2%A0switch(number)%20%7B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0case%201%3A%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0printf(%22One%22)%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0break%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0case%202%3A%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0printf(%22Two%22)%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0break%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0case%203%3A%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0printf(%22Three%22)%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0break%3B%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0default%3A%0A%0A%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0%C2%A0printf(%22Invalid%20Number%22)%3B%0A%0A%C2%A0%C2%A0%7D%0A%0Areturn%200%3B%0A%0A%7D" data-language="c" data-ace-language="c_cpp" data-name-language="C" data-main-file="main.c"><code>#include &lt;stdio.h&gt;

int main() {

  int number = 3;
  switch(number) {
    case 1:
      printf("One");
      break;

    case 2:
      printf("Two");
      break;

    case 3:
      printf("Three");
      break;

    default:
      printf("Invalid Number");
  }

return 0;
}</code></pre>
<p style="text-align: justify;"><span style="font-weight: 400;">Như vậy l&agrave; ta đ&atilde; học về c&aacute;c cấu tr&uacute;c điều khiển v&agrave; rẽ nh&aacute;nh để x&acirc;y dựng logic chương tr&igrave;nh. C&aacute;c bạn h&atilde;y luyện tập thật nhiều để th&agrave;nh thạo v&agrave; sử dụng n&oacute; l&agrave;m nền tảng cho c&aacute;c kiến thức ở c&aacute;c chương sau.</span></p>

Tổng kết cấu trúc điều khiển trong C