In this post, let's write a C program to multiply two matrices.

A prerequisite for multiplying two matrices is that the number of columns in the first matrix must be equal to the number of rows in the second matrix.

C Program to Multiply Two Matrices

#include <stdio.h>

int main()
{
  int matA[2][3], matB[3][4], matR[2][4];
  int i,j,k;

  printf("Enter elements of first matrix of order 2 x 3 \n");
  for(i=0;i<2;i++)
  {
    for(j=0;j<3;j++)
    {
      scanf("%d",&matA[i][j]);
    }
  }
  printf("Enter elements of second matrix of order 3 x 4 \n");
  for(i=0;i<3;i++)
  {
    for(j=0;j<4;j++)
    {
      scanf("%d",&matB[i][j]);
    }
  }
  for(i=0;i<2;i++)
  {
    for(j=0;j<4;j++)
    {
      matR[i][j]=0;
      for(k=0;k<3;k++)
      {
        matR[i][j]=matR[i][j]+matA[i][k]*matB[k][j];
      }
    }
  }
  printf("\nFirst Matrix is \n");
  for(i=0;i<2;i++)
  {
    for(j=0;j<3;j++)
    {
      printf("%d\t",matA[i][j]);
    }
    printf("\n");
  }
  printf("\nSecond Matrix is \n");
  for(i=0;i<3;i++)
  {
    for(j=0;j<4;j++)
    {
      printf("%d\t",matB[i][j]);
    }
    printf("\n");
  }
  printf("\nMatrix multiplication is \n");
  for(i=0;i<2;i++)
  {
    for(j=0;j<4;j++)
    {
      printf("%d\t",matR[i][j]);
    }
    printf("\n");
  }
  return 0;
}

Output:

Enter elements of the first matrix of order 2 x 3
3
9
7
1
5
4

Enter elements of the second matrix of order 3 x 4
6 2 8 1
3 9 4 0
5 3 1 3

First Matrix is
3 9 7 
1 5 4

Second Matrix is
6 2 8 1
3 9 4 0
5 3 1 3

Matrix multiplication is
80 108 67 24
41 59 32 13