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copied!<p>You have one of the closing parentheses in the wrong place:</p> <pre><code>(strcmp (argv[1], "-n" != 0)) </code></pre> <p>should be:</p> <pre><code>(strcmp (argv[1], "-n") != 0) </code></pre> <p>However, even once that's fixed, your argument processing is still not quite right.</p> <p>In <a href="https://stackoverflow.com/questions/12361558/c-basic-head-command">your previous question</a>, the <code>head -n COUNT FILE</code> was not a possibility, that made the argument checking reasonably easy.</p> <p>Here's the logic you need to follow now that you allow for a "floating" <code>-n count</code> section:</p> <pre><code>int linecount char *filename = NULL if argc == 2: linecount = 10 filename = argv[1] else: if argc == 4: if argv[1] == "-n": linecount = argv[2] filename = argv[3] else: if argv[2] == "-n": linecount = argv[3] filename = argv[1] if filename = NULL: generate some error </code></pre> <p>It basically catches the two-argument version first. If it's a four-argument version, it then finds out where the "-n" is so it can intelligently decide which argument is which value.</p> <p>As you can see, that's not quite what you have (your code looks for linecount in <code>argv[1]</code> which is <em>never</em> the case). You should use something like this as a guide:</p> <pre><code>argc argv[0] argv[1] argv[2] argv[3] ---- ------- ------- ------- ------- 2 head <file> 4 head <file> -n <count> 4 head -n <count> <file> </code></pre> <p>Once you refer to that, it should be easy to write the code for the different situations.</p> <p>You'll have to turn that pseudo-code of mine back into C of course (using <code>strcmp</code> instead of <code>==</code> for strings, and ensuring you use <code>atoi/strtol</code> for converting the string linecount argument to an integer), but that's the basic flow you should follow.</p>

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