title: How to cast const std::string& to integer?
body: <p>I have a variable like this:</p>
  
  <pre><code>const std::string&amp; iterations = "30";
  </code></pre>
  
  <p>I want to use it to determine number of iterations for a "for" loop:</p>
  
  <pre><code>for ( int i = 0; i &lt; iterations; i++ ) {
    // do something
  }
  </code></pre>
  
  <p>How to do that? I know I can cast to string like this:</p>
  
  <pre><code>iterations.c_str();
  </code></pre>
  
  <p>So I tried c_int() but it won't work:</p>
  
  <pre><code>iterations.c_int();
  </code></pre>