title: integer extraction from string
body: <p>I have an input argument string <code>const char* s</code>
  I know that it starts the sequence of chars which are  integers representation ,this sequence could be of any length ,including 0.
  After the integer sequence follows sequence of chars which are not integer representation.
  for example <code>"23meeting","1h"</code>.
  Is there some (builtin) C function which can extract the integer?
  For example for "23meeting" such operation could be performed : </p>
  
  <pre><code>int x = needed_function("23meeting"); //results x = 23
  </code></pre>
  
  <p>Thanks</p>