// An easier way to extract each character would be:
string s = "abcde";
for (int i=0; i<s.size(); i++) {
cout << s[i];
}
// To test if a particular character is an integer, you would do this:
//test if s[i] is an int from 0-9
if (s[i] <= '9' && s[i] >= '0') {
return true;
}