title: Why am I always getting a segmentation fault in this CS50 Pset?
body: <p>I am currently attempting Pset2 of CS50 and in <code>caesar.c</code>, the user is supposed to enter k through argv; if he doesn't I am supposed to "yell"
  at the user telling him to use command line  arguments. But if I try the following I ALWAYS get a segmentation fault.</p>
  
  <pre><code>#include &lt;cs50.h&gt;
  #include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  
  int main(int argc, const string argv[])
  {
      unsigned int k = atoi(argv[1]);
  
      if(k == NULL)
      {
          printf("YOU DID NOT INPUT ANYTHING AS COMMAND LINE ARGUMENT! ");
          return 1;
      }
  
      return 0;
  }
  </code></pre>