How to determine if a string is a number with C++?

Question

I\'ve had quite a bit of trouble trying to write a function that checks if a string is a number. For a game I am writing I just need to check if a line from the file I am r

Answer 1

Try this:

isNumber(const std::string &str) {    
  return !str.empty() && str.find_first_not_of("0123456789") == string::npos;
}