title: Convert std::string number in hexadecimal number
body: <p>I have searched online, but it doesn't seem to be a solution to my problem. Basically I have a <code>std::string</code> which contains a hexadecimal memory address (like 0x10FD7F04, for example). This number is read from a text file and saved as a <code>std::string</code>, obviously.</p>
  
  <p>I need to convert this string to an int value, but keeping the hex notation, <em>0x</em>. Is there any way to do this?</p>