Numerical value of string

Originally Posted by farah727rash

Hi all,

I am trying to find the numerical value of a string that stores a two digit number. I have found the numerical value of a char as:

char character;
cin >> character;
int number = character - 48; // Computing the numberical value of character entered
cout << "The number you entered is: " << number << endl << endl;

How do I do the same and find the numerical value of a string storing 2 digits? I know a way to do this using character arrays:
for (; *str != '\0' && *str >= '0' && *str <='9'; str++)
num = (num * 10) + (*str - '0');

But, I am not supposed to use if statements, character arrays, apstrings, or atoi in this program.

I am stumped. Any ideas?

Thanks,
Farah.