title: Global variables as arguments in function C
body: <p>I have a list of global variables like this:</p>
  <pre><code>int a, b, c, d;
  </code></pre>
  <p>These variables are used in functions designed to count them, like:</p>
  <pre><code>int my_func(string x)
  {
   //count var a//
  }
  </code></pre>
  <p>Now I would like to use 'a' and e.g. 'b' as an arguments for another function which I declare this way:</p>
  <pre><code>int multiplication(int a, int b);
  </code></pre>
  <p>and define this way:</p>
  <pre><code>int multiplication(int a, int b)
  {
  c = a * b;
  return c;
  }
  </code></pre>
  <p>When I run it, I get the below error:</p>
  <pre><code> ac.c:75:27: error: declaration shadows a variable in the global scope [-Werror,-Wshadow]
  int multiplication(int a, int b)
                         ^
  ac.c:7:41: note: previous declaration is here
  int a, b, c, d;
  </code></pre>
  <p>How can I fix it? When I try to declare those variables inside functions, the whole program returns many errors.</p>