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    <p>First things first, your usage doesn't match your argument checking. According to the usage, you must use one of:</p> <pre><code>head &lt;filename&gt; head &lt;filename&gt; -n &lt;count&gt; </code></pre> <p>In other words, <code>argv[1]</code> is <em>always</em> the filename, <code>argv[2]</code> is the one that needs to be set to <code>-n</code> if there are more than two arguments.</p> <p>Secondly, unless you want to use VLAs (variable length arrays), you should probably just set up a pointer to the filename argument with something like:</p> <pre><code>char *fileName = argv[1]; </code></pre> <p>You don't need to change it at all (you'll just be passing it to <code>fopen</code>, presumably), so it's a waste trying to make another copy.</p> <p>In addition, your <code>if</code> statement is wrong as an <code>or</code>, it should be an <code>and</code>. It's guaranteed that <code>argc</code> will either not be 2 or not be 4, since it can't be both at the same time.</p> <p>I would start with something like:</p> <pre><code>#include &lt;stdio.h&gt; #include &lt;stdlib.h&gt; #include &lt;string.h&gt; static int usage (void) { printf ("Usage: head &lt;file&gt;\n"); printf (" or: head &lt;file&gt; -n &lt;number of characters&gt;\n"); return -1; } int main (int argc,char *argv[]) { char *fileName; int lineCount; // Checks if correct arguments if ((argc != 2) &amp;&amp; (argc != 4)) return usage(); if ((argc == 4) &amp;&amp; (strcmp(argv[2], "-n" != 0)) return usage(); // Get file spec and line count fileName = argv[1]; lineCount = (argc == 2) ? 10 : atoi (argv[3]); // or strtol for purists if (linecount &lt; 0) lineCount = 0; // Now go ahead and implement the logic for head. } </code></pre>
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    1. COand note that with this approach `fileName` is _not_ a deep copy of argv[1] - it's just a pointer that shares its contents with argv[1]. This is OK since argv[] is usually never deallocated. In other situations, this is one of the "gotchas" of C.
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    2. CO"Usually" never deallocated? I would say "never", at least not until after `main` returns (or your program exits some other way).
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