title: can size of array be determined at run time in c?
body: <p>As I know, an array needs to have a specific size before compiling time in c. </p>
  
  <p>I wonder why this code still works?</p>
  
  <pre><code>int s;
  printf("enter the array size: ");
  scanf("%d",&amp;s);
  
  int a[s]; // Isn't s value determined at run time?
  </code></pre>