string a;
unsigned short int Sum=0,i;
a="12522";
for(i=0;i<a.length();i++)
{
string b;
b=a[i];
 Sum+=atoi(b.c_str())];
}

48%2=0;

48,
4+8=12;//SUM OF DIGITS
12%2=0// even

int sum_digits(int number)
{
    int remainder = number%10;
    if (remainder > 0)
        return remainder+sum_digits((number-remainder)/10);
    else if (number >= 10 && remainder == 0)
        return sum_digits(number/10);
    return number;
}
 
bool sum_digits_even(int number)
{
    return !(sum_digits(number) % 2);
}

bool isEven(const char* number)
{
    bool even = false;
    if (number) {
        if (*number == '-' || *number == '+')
            number++;
        if (*number) {
            even = true;
            do switch (*number++) {
                case '1': case '3': case '5': case '7': case '9':
                    even = !even; 
                    continue;
                case '0': case '2': case '4': case '6': case '8':
                    continue;
                default: return false; // not a number
            } while (*number);
        }
    }
    return even;
}
inline
bool isEven(const std::string& number) {
    return isEven(number.c_str());
}
/// for true integers:
bool isEven(unsigned long number)
{
    std::string buff;
    std::ostringstream is(buff);
    (is << number).flush(); 
    return isEven(buff);
}
using std::cout;
using std::cin;
void TestEven()
{
    std::string line;
    while (cout << "Integer: ",std::getline(cin,line))
        cout << isEven(line) << '\n';
}