title: Checking the format of a string
body: <p>I have a vector of strings im working trought, and i need to check how the string is formated. 
  Im using sscanf in the rest of the function and i need something like this.</p>
  
  <pre><code>if (format("%f,%f,%f")) {
    // Do someting
  } else if (format("%d,%d")) {
    // Do something else
  } else {
    // Do something
  }
  </code></pre>
  
  <p>Is this possible using sscanf or something else from std?</p>