Assignment : Adding and substracting out of range numbers in C++ (Assigned by : Hanif sir)

// Hello stranger. ^_^

#include<iostream>

#include<algorithm>

#include<string>

using namespace std;

main(void)

{

    int g = 0 , ca = 0 , si;

    string a , b , c , blank;

    cin >> a >> b;

    si = max(a.size() , b.size());

    if(a < b)

        swap(a , b);

    if(a.size() < b.size())

    {

        blank.resize(si - a.size());

        a = blank + a;

    }

    else

    {

        blank.resize(si - b.size());

        b = blank + b;

    }

    c.resize(si + 1);

    for(int i = si - 1 , k = 0 ; i >= 0 ; i-- , k++)

    {

        if(isdigit(a.at(i)) == true and isdigit(b.at(i)) == true)

            c.at(k) = a.at(i) + b.at(i) - 48 + ca;

        else if(isdigit(a.at(i)) == true and isdigit(b.at(i)) == false)

            c.at(k) = a.at(i) + ca;

        else if(isdigit(b.at(i)) == true and isdigit(a.at(i)) == false)

            c.at(k) = b.at(i) + ca;

        ca = 0;

        if(c.at(k) - 48 >= 10)

        {

            c.at(k) = c.at(k) - 10;

            ca = 1;

            g++;

        }

    }

    reverse(c.begin() , c.end());

    if(ca == 1)

        c.at(0) = '1';

    else

        c.erase(c.begin());

    if(a < b)

        swap(a , b);

    cout << ' ' << a << endl << '+' << b << endl;

    for(int i = 0 ; i <= c.size() ; i++)

        cout << '-';

    cout << endl << c << endl << "Number of Carries: " << g << endl;

}

// Minor changes for subtractions.

//You may want to combine both of them together.

//But I reckon making a project will help since linkers work faster than a gigantic diver code.

#include<iostream>
#include<algorithm>
#include<string>

using namespace std;

main(void)
{
    int g = 0 , ca = 0 , si , t = 0;
    string a , b , c , blank;
    cin >> a >> b;
    if(a < b)
    {
        swap(a , b);
        t = 1;
    }
    si = max(a.size() , b.size());
    if(a.size() < b.size())
    {
        blank.resize(si - a.size());
        a = blank + a;
    }
    else
    {
        blank.resize(si - b.size());
        b = blank + b;
    }
    c.resize(si + 1);
    for(int i = si - 1 , k = 0 ; i >= 0 ; i-- , k++)
    {
        if(isdigit(a.at(i)) == true and isdigit(b.at(i)) == true)
            c.at(k) = a.at(i) - b.at(i) + 48 - ca;
        else if(isdigit(a.at(i)) == true and isdigit(b.at(i)) == false)
            c.at(k) = a.at(i) - ca;
        else if(isdigit(b.at(i)) == true and isdigit(a.at(i)) == false)
            {
                c.at(k) = b.at(i);
                ca = 1;
                continue;
            }
        ca = 0;
        if(c.at(k) < 48)
        {
            c.at(k) += 10;
            ca = 1;
            g++;
        }
    }
    reverse(c.begin() , c.end());
    if(ca == 1 or t == 1)
        c.at(0) = '-';
    else
        c.erase(c.begin());
    if(a < b)
        swap(a , b);
    cout << ' ' << a << endl << '-' << b << endl;
    for(int i = 0 ; i <= c.size() ; i++)
        cout << '-';
    cout << endl << c << endl << "Number of Carries: " << g << endl;
}

// Don't follow my code. It's completely composed out of brute force. Learn algorithm for these type of programs , which I'm still learning. ^_^