program to multiply two matrices

 #include <iostream>

using namespace std;

class multi

{

    int a[10][10], b[10][10], mult[10][10], r1, c1, r2, c2, i, j, k;

   

public:

    multi(int r1, int c1, int r2, int c2)

    {

        this->r1 = r1;

        this->c1 = c1;

        this->r2 = r2;

        this->c2 = c2;

        int a[r1][c1], b[r2][c2];

    }

    void matrix()

    {

        // Storing elements of first matrix.

        cout << endl

             << "Enter elements of matrix 1:" << endl;

        for (i = 0; i < r1; ++i)

            for (j = 0; j < c1; ++j)

            {

                cout << "Enter element a" << i + 1 << j + 1 << " : ";

                cin >> a[i][j];

            }

        // Storing elements of second matrix.

        cout << endl

             << "Enter elements of matrix 2:" << endl;

        for (i = 0; i < r2; ++i)

            for (j = 0; j < c2; ++j)

            {

                cout << "Enter element b" << i + 1 << j + 1 << " : ";

                cin >> b[i][j];

            }

    }

    void multip()

    {

        // Initializing elements of matrix mult to 0.

        for (i = 0; i < r1; ++i)

            for (j = 0; j < c2; ++j)

            {

                mult[i][j] = 0;

            }

        // Multiplying matrix a and b and storing in array mult.

        for (i = 0; i < r1; ++i)

            for (j = 0; j < c2; ++j)

                for (k = 0; k < c1; ++k)

                {

                    mult[i][j] += a[i][k] * b[k][j];

                }

        // Displaying the multiplication of two matrix.

        cout << endl

             << "Output Matrix: " << endl;

        for (i = 0; i < r1; ++i)

        {

            for (j = 0; j < c2; ++j)

            {

                cout << " " << mult[i][j];

            }

            cout << endl;

        }

    }

};

int main()

{

    int r1, c1, r2, c2;

    cout << "Enter rows and columns for first matrix: ";

    cin >> r1 >> c1;

    cout << "Enter rows and columns for second matrix: ";

    cin >> r2 >> c2;

    // If column of first matrix in not equal to row of second matrix,

    // ask the user to enter the size of matrix again.

    while (c1 != r2)

    {

        cout << "Error! column of first matrix not equal to row of second.";

        cout << "Enter rows and columns for first matrix: ";

        cin >> r1 >> c1;

        cout << "Enter rows and columns for second matrix: ";

        cin >> r2 >> c2;

    }

    multi obj(r1, c1, r2, c2);

    obj.matrix();

    obj.multip();

    return 0;

}