title: why does long long 2147483647 + 1 = -2147483648?
body: <p>Why doesn't this code print same number? : </p>
  
  <pre><code>long long a, b;
  a = 2147483647 + 1;
  b = 2147483648;
  printf("%lld\n", a);
  printf("%lld\n", b);
  </code></pre>
  
  <p>I know that int variable's maximum number is 2147483647 because int variable is 4 byte.
  But as I know, long long variable is 8 byte, but why does that code act like that?</p>