title: Wrong strlen output
body: <p>I have the following piece of code in C:</p>
  
  <pre><code>char a[55] = "hello";
  size_t length = strlen(a);
  char b[length];
  strncpy(b,a,length);
  size_t length2 = strlen(b);
  printf("%d\n", length);          // output = 5
  printf("%d\n", length2);         // output = 8
  </code></pre>
  
  <p>Why is this the case?</p>