I have coded this program to get two matrices and in a different function, it calculates the addition of the two matrices, but when I want to get the two arrays as input arguments in my "sum" function it generates errors and it doesn't work.

My efforts include reviewing this question at Stackoverflow : Passing a 2D array to a C function It helps if only I set A and B arrays with numerical dimensions like : A[2][2] not A[ar][ac]. I want the function to work for n*n matrices not up to a limited number.

#include <iostream>
#include <iomanip>
using namespace std;

template <size_t row, size_t column, size_t row2, size_t column2 >
void sum(int(&array)[row][column], int(&array2)[row2][column2]);

int main()
{
    int ar, ac, br, bc;
    
    cout << "Welcome to my matrix calculator. \nPlease enter the values of you matrices.";
    cout << "\n\n\tFor your FIRST matrix;";
    cout << "\n\tNumber of \'ROWS\' : ";
    cin >> ar;
    cout << "\tNumber of \'COLUMNS\' : ";
    cin >> ac;
    
    int A[ar][ac];
    
    cout << "\n\tPlease enter the values of your matrix." << endl << endl;
    
    for (int i=0; i<ar; i  )
    {
        for (int j=0; j<ac; j  )
        {
            int m = i;
            m  ;
            int n = j;
            n  ;
            
            cout << "\tNumber[" << m << "][" << n << "] : ";
            cin >> A[i][j];
        }
        cout << endl;
    }
    
    
    cout << "\n\tFor your SECOND matrix;";
    cout << "\n\tNumber of \'ROWS\' : ";
    cin >> br;
    cout << "\tNumber of \'COLUMNS\' : ";
    cin >> bc;
    
    int B[br][bc];
    
    cout << "\n\tPlease enter the values of your matrix." << endl << endl;
    
    for (int i=0; i<br; i  )
    {
        for (int j=0; j<bc; j  )
        {
            int m = i;
            m  ;
            int n = j;
            n  ;
            
            cout << "\tNumber[" << m << "][" << n << "] : ";
            cin >> B[i][j];
        }
        cout << endl;
    }
    

    cout << "\nYour FIRST matrix is : " << endl;
    
    for (int i=0; i<ar; i  )
    {
        cout << endl  << "\t" << "|";
        for (int j=0; j<ac; j  )
        {
            cout << setw(4) << A[i][j];
        }
        cout << "  |";
    }
    
    cout << "\n\nYour SECOND matrix is : " << endl;
    
    for (int i=0; i<br; i  )
    {
        cout << endl  << "\t" << "|";
        for (int j=0; j<bc; j  )
        {
            cout << setw(4) << B[i][j];
        }
        cout << "  |";
    }
    
    sum(A, B);
}


template <size_t row, size_t column, size_t row2, size_t column2 >
void sum(int(&array)[row][column], int(&array2)[row2][column2])
{
    if(row==row2 && column==column2)
    {
        cout << "\n\n\tThe addition of your matrices is = ";
        int add[row][column];
        
        for(int i=0; i<row; i  )
        {
            for(int j; j<column; j  )
            {
                add[i][j] = array[i][j]   array2[i][j];
            }
        }
        
        for(int i=0; i<row; i  )
        {
            cout << endl  << "\t" << "|";
            for(int j=0; j<column; j  )
            {
                cout << setw(4) << add[i][j];
            }
            cout << "  |";
        }
    }
    
    else
    {
        cout<< "Matrixes with different rows and columns can \'not\' be added together.";
    }
}

I did try whatever was on the internet but none of work for n*n matrices, could you please help? Thanks in advance!

CodePudding user response：

You could just interpret a 1-dimensional array as two-dimensional (one row after another)

// To allocate the array, multiply the number of rows by the number of columns
int *A = new int[ar * ac];
int *B = new int[br * bc];

// To access [i][j], multiply i by the number of columns, and add j
A[(i*ac)   j] = x;

sum(A, ar, ac, B, br, bc);

// don't forget to delete the arrays (because you new'd them)
delete[] A;
delete[] B;

// ....

void sum (int *array1, size_t r1, size_t c1, int *array2, size_t r2, size_t c2) {
   // check for compatibility, nested loop and then ....  
   add[c1 * i   j] = array1[c1 * i   j]   array2[c1 * i   j];
   // ....
}

Leaving out a lot of code, but hopefully you get the idea.

This is how to do it with just regular int arrays. To do complex matrix stuff, you should be building up a custom class that hides the details and makes it easier to just think of the objects as 2-d matrices.