Urgent Help Please.

[Little Girl]

C++ Help Required.

the user puts in some numbers and we read it and store it in reversed.. cuz we need to add the arrays.. and when we r adding we have to make sure if there is a carry we include that and so on.. and let's say the user entered 1 number to be 4 digits and 2nd number to be 4 digits.. and we globally declared that max allowed will be 4 but if their sum end up being 5 digits then we have to give error that it over flows.. and if their sum is within the boundary then print out the sum on the screen

this is what I have for the read function'

bool ReadBigInt(BigInt& num)
{
string s;
cin >> s;
int len = s.length();
if (len > MAX_DIGITS)
return false;
else
for (int i = len - 1; i >= 0; i--)
num.Digits[len-i-1] = s[i] - '0';
return true;

I need to write one function for printing and one for adding.. but I can't figure out how to do the sum with the carry and so on in actual problem max will be 50 digits so we have to write a function in general tht will work with however many digits user enters from 1 to 50. to test the program we will change the max to 4 or 5 to see if the program runs properly


If you can't help me regarding code please tell me some logically points ill try to code myself.