_newAlc for hex to dec

int _hextodec()
{
    const int size = 16;
    long long int power[size], pow = 1;
    long long int dec = 0;

    char hex[size] = {};
    cout << "Введите шестнадцатиричное (hexadecimal) число -> "; cin >> hex; cout << endl;

    for (int i = 0; i < size; i++)
    {
        power[i] = pow;
        pow *= 16;
    }

    //int i = 0;

    //for (int i = 0; i < size; ((hex[i] == 'A') ? hex[i] = (int)10 : (hex[i] == 'B') ? hex[i] = (int)11 : (hex[i] == 'C') ? hex[i] = (int)12 : (hex[i] == 'D') ? hex[i] = (int)13 :
    //  (hex[i] == 'E') ? hex[i] = (int)14 : (hex[i] == 'F') ? hex[i] = (int)15 : /* (hex[i] <= 0) ? hex[i] *= (int)0 : */ hex[i] = (char)hex[i] - 48), i++);
    int Digits = 0;
    for (int i = 0; hex[i] != 0; i++)
    {
        if (hex[i] >= 65 && hex[i] <= 70) hex[i] -= 55;
        else if (hex[i] >= 97 && hex[i] <= 102) hex[i] -= 87;
        else if (hex[i] >= 48 && hex[i] <= 57) hex[i] -= 48;
        Digits++;
    }

    for (int i = 0; i < Digits; i++)
    {
        dec = dec + hex[Digits - 1 - i] * power[i];
    }

    /*for (int i = size - 1, j = 0; i >= 0; i--)
    {
        if (hex[i] > 0) dec = dec + ((int)hex[i] * power[j++]);
    }*/

    cout << "Decimal: " << dec << endl << endl;

    return 0;
}