title: Check if string contains a range of numbers
body: <p>I'd like to test a <code>std::string</code> for containing numbers of any range e.g <code>5 to 35</code> in a <code>std::string s = "XDGHYH20YFYFFY"</code> would there be function or I would have to convert a number to string and then use a loop to find each one?</p>