title: Function to check if string contains a number
body: <p>I'm working on a project in c++ (which I just started learning) and can't understand why this function is not working. I'm attempting to write a "Person" class with a variable first_name, and use a function set_first_name to set the name. Set_first_name needs to call a function(the one below) to check if the name has any numbers in it. The function always returns false, and I'm wondering why? Also, is this the best way to check for numbers, or is there a better way?</p>
  
  <pre><code>   bool Person::contains_number(std::string c){ // checks if a string contains a number
          if (c.find('0') == std::string::npos || c.find('1') == std::string::npos || c.find('2') == std::string::npos || c.find('3') == std::string::npos
          || c.find('4') == std::string::npos || c.find('5') == std::string::npos || c.find('6') == std::string::npos || c.find('7') == std::string::npos
          || c.find('8') == std::string::npos || c.find('9') == std::string::npos){// checks if it contains number
  
          return false;
          }
          return true;
      }
  </code></pre>