Multiply Two Matrices in C++

In this tutorial, we will be discussing a program to multiply two matrices.

For this we will be given with two matrices and our task is to print the product of two those matrices. The only condition is that the number of columns of first matrix should be equal to the number of rows of the second matrix.

Example

 Live Demo

#include <iostream>
using namespace std;
#define N 4
//multiplying the elements of both matrices
void calc_product(int mat1[][N], int mat2[][N], int res[][N]){
   int i, j, k;
   for (i = 0; i < N; i++) {
      for (j = 0; j < N; j++){
         res[i][j] = 0;
         for (k = 0; k < N; k++)
            res[i][j] += mat1[i][k] * mat2[k][j];
      }
   }
}
int main(){
   int i, j;
   int res[N][N];
   int mat1[N][N] = {{1, 1, 1, 1},
      {2, 2, 2, 2},
      {3, 3, 3, 3},
      {4, 4, 4, 4}};
   int mat2[N][N] = {{1, 1, 1, 1},
      {2, 2, 2, 2},
      {3, 3, 3, 3},
      {4, 4, 4, 4}};
   calc_product(mat1, mat2, res);
   cout << "Resultant matrix :\n";
   for (i = 0; i < N; i++){
      for (j = 0; j < N; j++)
      cout << res[i][j] << " ";
      cout << "\n";
   }
   return 0;
}

Output

Resultant matrix :
10 10 10 10
20 20 20 20
30 30 30 30
40 40 40 40