title: mixture of string and number in macro
body: <p>I want to use this macro to put (if 'i' is greater than zero) the symbol '^' and the number I pass (i) to the macro</p>
  
  <pre><code>#define ESP(i) ((i&gt;0) ? ("^"(i)) : "")
  </code></pre>
  
  <p>I want to call it in this way</p>
  
  <pre><code>printf("%+d%s", n1, ESP(i));
  </code></pre>
  
  <p>where 'i' is the index of a cycle, but the compilation reports me errors;
  how can I modify the code to be right?</p>