title: Functions used by one function in header file
body: <p><strong>Context</strong></p>
  
  <p>I'm writing a function that uses other functions which are only needed in that main function. The purpose of that main function is to make some sort of kit that will call the required functions.</p>
  
  <p><strong>Exemple</strong></p>
  
  <pre><code>int a(int x) // make x = 10 in a recursive way and its purpose is limited 
               // to be used with function b
  {
      if (x == 10) return x;
      else if(x&lt;10) return a(x+1);
      else return a(x-1);
  }
  
  int b(int x, int allow_b) // This is only an exemple, function b simply call function a if required.
  {
      if (allow_b == 1) return a(x);
      else return x;
  }
  </code></pre>
  
  <p><strong>Question</strong></p>
  
  <p>Since function 'a' only exist to be used by 'b', should there be something particular to be done in the header file or it should only be commented over the function 'a' is used by 'b' ?</p>
  
  <p>Is there something wrong with that kind of approach?</p>
  
  <p><strong>Edit</strong></p>
  
  <p>I mean what should be declared in header, I'm not talking about writing function 'a' and 'b' in header file.</p>