title: Implicit declaration of function abs - gcc-5.1.0
body: <p>Compiling the following code using gcc-5.1.0 produces a warning:</p>
  
  <pre><code>warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration]
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;math.h&gt;
  
  int main (void)
  {
    printf ("%d\n", abs (-1));
  
    return 0;
  }
  </code></pre>
  
  <p>I have compiled the same code with gcc-4.9.2 and it's not producing any warning.</p>