title: Why "unsigned int64_t" gives an error in C?
body: <p>Why the following program gives an error?</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  
  int main() 
  {
      unsigned int64_t i = 12;
      printf("%lld\n", i);
      return 0;
  }
  </code></pre>
  
  <p><strong>Error:</strong></p>
  
  <pre><code> In function 'main':
  5:19: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'i'
    unsigned int64_t i = 12;
                     ^
  5:19: error: 'i' undeclared (first use in this function)
  5:19: note: each undeclared identifier is reported only once for each function it appears in
  </code></pre>
  
  <p>But, If I remove the <strong>unsigned</strong> keyword, it's working fine. So,
  <strong>Why <code>unsigned int64_t i</code> gives an error?</strong></p>