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

The simplest I can think of in c++

bool isNumber(string s) {
    if(s.size()==0) return false;
    for(int i=0;i='0' && s[i]<='9')==false) {
            return false;
        }
    }
    return true;
}

Working code sample: https://ideone.com/nRX51Y