title: About Rot13-Implementation
body: <p>I am trying to implement the rot13-algorithm in C.
  But since I am not very familiar with that language, I have some problems with my code right here.</p>
  
  <p>Basically, I want to rotate every letter in args[] to 13 positions up.
  But this code seems to be pretty sluggish:</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  
  char[] rotate(char c[]) {
    char single;
    int i;
    int alen = sizeof(c)/sizeof(c[0]);
    char out[alen];
  
    for(i=0;i&lt;=alen;i+=1) {
      if(c[i]&gt;='a' &amp;&amp; (c[i]+13)&lt;='z'){
        out[i] = c[i]+13;
      }
    }
  
    return out;
  }
  
  int main(int argc, char *argv[]) {
    printf("The given args will be rotated\n");
    int i;
    char rotated[sizeof(argv)/sizeof(argv[0])];
  
    rotated = rotate(argv);
  
    /* printing rotated[] later on */
    return 0;
  
  }
  </code></pre>
  
  <p>I know there a lot of holes here - could you show me how to fix this?</p>