title: Macro for concatenating two strings in C
body: <p>I'm trying to define a macro which is suppose to take 2 string values and return them concatenated with a one space between them. It seems I can use any character I want besides space, for example:</p>
  
  <pre><code>#define conc(str1,str2) #str1 ## #str2 
  #define space_conc(str1,str2) conc(str1,-) ## #str2
  
  space_conc(idan,oop);
  </code></pre>
  
  <p><code>space_conc</code> would return "idan-oop"</p>
  
  <p>I want something to return "idan oop", suggestions?</p>