title: best way to add char* prefix to existing char* in C
body: <p>What I have: </p>
  
  <pre><code>char * a = "world";
  char * b = "Hello";
  </code></pre>
  
  <p>What I need is: </p>
  
  <pre><code>char * a = "Hello World";
  </code></pre>
  
  <p>I need to add b before a.
  Is there any function that doing it?</p>