<p>I have a library I created,</p>
<h3>File <em>mylib.c:</em></h3>
<pre><code>#include &lt;mylib.h&gt;

int
testlib() {
    printf(&quot;Hello, World!\n&quot;);
    return (0);
}
</code></pre>
<h3>File <em>mylib.h:</em></h3>
<pre><code>#include &lt;stdio.h&gt;
extern int testlib();
</code></pre>
<p>In my program, I've attempted to call this library function:</p>
<h3>File <em>myprogram.c</em>:</h3>
<pre><code>#include &lt;mylib.h&gt;

int
main (int argc, char *argv[]) {
    testlib();
    return (0);
}
</code></pre>
<p>When I attempt to compile this program I get the following error:</p>
<pre>In file included from myprogram.c:1
mylib.h:2 warning: function declaration isn't a prototype</pre>
<p>I'm using: <code>gcc (GCC) 3.4.5 20051201 (Red Hat 3.4.5-2)</code></p>
<p>What is the proper way to declare a function prototype?</p>

Try:
```
```
extern int testlib(void);
```
```