A little help with matrix multiplication

[Ysharma]

I've been assigned to build a program which completes mathematical operations using matrices. I have to use dynamically allocated 2d arrays, and can only use * to dereference and not []. I have this code so far, but the multiply_matrix function does not work with most values. I've looked at other similar posts, which have a similar algorithm to mine, but mine does not work for some reason.

/*




*(*matrix(matrix+i)+j)

*/

#include <iostream>
//for sleep() which allows user to see messages before screen is cleared
#include <unistd.h>
using namespace std;

//xcode does not allow for using system("cls")
void cls();
void promptnew(int&, int&, int&, int&);
int** creatematrix(int, int);
void fillmatrix(int**, int, int, short);
void displaymatrix(int**, int, int);
void clearmatrix(int**, int , int);
void add_matrix(int**, int**, int, int, int, int);
void subtract_matrix(int**, int**, int, int, int, int);
void multiply_matrix(int**, int**, int, int, int, int);

int main()
{
    int _1matrix_row;
    int _1matrix_column;
    int _2matrix_row;
    int _2matrix_column;
    int** usermatrix1;
    int** usermatrix2;
    short menu_choice;

thebigbang:

    promptnew(_1matrix_row, _1matrix_column, _2matrix_row, _2matrix_column);
    usermatrix1 = creatematrix(_1matrix_column, _1matrix_row);
    usermatrix2 = creatematrix(_2matrix_column, _2matrix_row);
    fillmatrix(usermatrix1, _1matrix_row, _1matrix_column, 1);
    fillmatrix(usermatrix2, _2matrix_row, _2matrix_column, 2);
    
    //runs menu until exit option is choice
    do
    {
        
        //menu after correct pin is entered
        do
        {
            cout << "*** Welcome to the Matrix Math Calculator ****\n"
            << "1. Add two matrices\n"
            << "2. Subtract two matrices\n"
            << "3. Multiply two matrices\n"
            << "4. Clear and enter new matrices\n"
            << "5. Exit\n";
            cout << "Choose an option: ";
            cin >> menu_choice;
            
            //input validation
            if (menu_choice < 1 || menu_choice > 5)
            {
                cout << "Invalid selection, please select an option from the menu\n";
                //allows user to see error before proceeding
                sleep(3);
                cls();
            }
        }
        while(menu_choice < 1 || menu_choice > 5);
        
        if (menu_choice == 1)
        {
            cls();
            add_matrix(usermatrix1, usermatrix2, _1matrix_row, _1matrix_column, _2matrix_row, _2matrix_column);
            sleep(5);
            cls();
        }
        
        else if (menu_choice == 2)
        {
            cls();
            subtract_matrix(usermatrix1, usermatrix2, _1matrix_row, _1matrix_column, _2matrix_row, _2matrix_column);
            sleep(5);
            cls();
        }
        
        else if (menu_choice == 3)
        {
            cls();
            multiply_matrix(usermatrix1, usermatrix2, _1matrix_row, _1matrix_column, _2matrix_row, _2matrix_column);
            sleep(5);
            cls();
        }
        
        else if (menu_choice == 4)
        {
            cls();
            clearmatrix(usermatrix1, _1matrix_row, _1matrix_column);
            clearmatrix(usermatrix2, _2matrix_row, _2matrix_column);
            goto thebigbang;
        }
        else if (menu_choice == 5)
        {
            clearmatrix(usermatrix1, _1matrix_row, _1matrix_column);
            clearmatrix(usermatrix2, _2matrix_row, _2matrix_column);
            return 0;
        }
    }
    while (menu_choice != 5);
}

void promptnew(int& _1matrix_row, int& _1matrix_column, int& _2matrix_row, int& _2matrix_column)
{
    do
    {
        cout << "Enter the number of rows and columns in the first matrix, one by one, with enters in between: ";
        cin >> _1matrix_row >> _1matrix_column;
        if (_1matrix_column <= 0 || _1matrix_row <= 0)
        {
            cout << "Enter a valid number of rows and columns" << endl;
            sleep(3);
            cls();
        }
        
    }
    while (_1matrix_column < 1 || _1matrix_row < 1);
    
    do
    {
        cout << "Enter the number of rows and columns in the second matrix, one by one, with enters in between: ";
        cin >> _2matrix_row >> _2matrix_column;
        if (_2matrix_column <= 0 || _2matrix_row <= 0)
        {
            cout << "Enter a valid number of rows and columns" << endl;
            sleep(3);
            cls();
        }
    }
    while (_2matrix_column < 1 || _2matrix_row < 1);
}

int** creatematrix(int column, int row)
{
    int** matrix = new int* [row];
    for (int count = 0; count < row; count++)
    {
        matrix[count] = new int [column];
    }
    return matrix;
}

void fillmatrix(int** matrix, int row, int column, short a)
{
    for (int rowcount = 0; rowcount < row; rowcount++)
    {
        for (int colcount = 0; colcount < column; colcount++)
        {
            cout << "Filling the " << a << " matrix\n";
            cout << "Enter the value of the " << (rowcount + 1) << " row and the " << (colcount+1)
                 << " column: \n";
            cin >> *(*(matrix+rowcount)+colcount);
        }
    }
}

void displaymatrix(int** matrix, int row, int column)
{
    for (int rowcount = 0; rowcount < row; rowcount++)
    {
        for (int colcount = 0; colcount < column; colcount++)
        {

            cout << *(*(matrix+rowcount)+colcount) << "\t";
        }
        cout << "\n";
    }
}

void clearmatrix(int** removal_que, int row, int column)
{
    for (int process = (row-1); process >= 0; process--)
    {
        delete [] removal_que[process];
    }
    removal_que = NULL;
}

void add_matrix(int** mat1, int** mat2, int row1, int col1, int row2, int col2)
{
    if (row1 != row2 || col1 != col2)
    {
        cout << "MAJOR ERR: You must enter valid matrice dimensions, both rows and columns must be equal for addition\n";
        sleep(5);
        clearmatrix(mat1, row1, col1);
        clearmatrix(mat2, row2, col2);
        exit(1);
    }
    int** answer = creatematrix(col1, row1);
    for (int rowcount = 0; rowcount < row1; rowcount++)
    {
        for (int colcount = 0; colcount < col1; colcount++)
        {
            
            *(*(answer+rowcount)+colcount) = *(*(mat1+rowcount)+colcount) + *(*(mat2+rowcount)+colcount);
        }
    }
    cout << "The answer is:  \n\t--Solution Matrix--\n";
    displaymatrix(answer, row1, col2);
    
}

void subtract_matrix(int** mat1, int** mat2, int row1, int col1, int row2, int col2)
{
    if (row1 != row2 || col1 != col2)
    {
        cout << "MAJOR ERR: You must enter valid matrice dimensions, both rows and columns must be equal for addition\n";
        sleep(5);
        clearmatrix(mat1, row1, col1);
        clearmatrix(mat2, row2, col2);
        exit(1);
    }
    int** answer = creatematrix(col1, row1);
    for (int rowcount = 0; rowcount < row1; rowcount++)
    {
        for (int colcount = 0; colcount < col1; colcount++)
        {
            
            *(*(answer+rowcount)+colcount) = *(*(mat1+rowcount)+colcount) - *(*(mat2+rowcount)+colcount);
        }
    }
    cout << "The answer is:  \n\t--Solution Matrix--\n";
    displaymatrix(answer, row1, col2);
    
}

void multiply_matrix(int** mat1, int** mat2, int row1, int col1, int row2, int col2)
{
    if (col2 != row1)
    {
        cout << "MAJOR ERR: You must enter valid matrice dimensions, both rows and columns must be equal for addition\n";
        sleep(5);
        clearmatrix(mat1, row1, col1);
        clearmatrix(mat2, row2, col2);
        exit(1);
    }
    int** answer = creatematrix(col2, row1);
    for (int rowcount = 0; rowcount < row1; rowcount++)
    {
        for (int colcount = 0; colcount < col2; colcount++)
        {
            for (int cound = 0; cound < col2; cound++)
            {
                *(*(answer+rowcount)+colcount) += ( *(*(mat1+rowcount)+cound) * *(*(mat2+cound)+colcount) );
            }
        }
    }
    cout << "The answer is:  \n\t--Solution Matrix--\n";
    displaymatrix(answer, row1, col2);
}

void cls()
{
    for (short count =1; count <= 100; count++)
    {
        cout << "\n";
    }
}

[Peter87]

The elements of the matrix has not been initialized.