Сумма цифр в строке

# include  <stdio.h>
# include <conio.h>
# include <iostream>
# include "stdafx.h"
using namespace std;
int main()
{
	char str[80];
	int sum = 0,i=0;
	gets(str);
	while (str[i] && str[i] != '\n')
	{
		if (str[i] >= '0'  &&  str[i] <= '9')
			sum += str[i] - '0';
		i++;
	}
	cout << "Sum =" << sum;
	system("pause");
	return 0;
}