Write C++ Program to Multiply Two Matrices

Introduction

I have used CodeBlocks compiler for debugging purpose. But you can use any C++ programming language compiler as per your availability.

#include <iostream>
using namespace std;
 
int main()
{
        int a[10][10], b[10][10], result[10][10], r1, c1, r2, c2, i, j, k;
 
        cout<<"Enter rows and column for first matrix: ";
        cin>>r1;
        cin>>c1;
 
        cout<<"Enter rows and column for second matrix: ";
        cin>>r2;
        cin>>c2;
 
         // Column of first matrix should be equal to column of second matrix and
         while (c1 != r2)
        {
        cout<<"Error! column of first matrix not equal to row of second.\n\n";
        cout<<"Enter rows and column for first matrix: ";
        cin>>r1;
        cin>>c1;
        cout<<"Enter rows and column for second matrix: ";
        cin>>r2;
        cin>>c2;
        }
 
        // Storing elements of first matrix.
        cout<<"\nEnter elements of matrix 1:\n";
        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<<"\nEnter elements of matrix 2:\n";
        for(i=0; i<r2; ++i)
        for(j=0; j<c2; ++j)
        {
            cout<<"Enter element b"<<i+1<<j+1<<": ";
            cin>>b[i][j];
        }
 
        // Initializing all elements of result matrix to 0
        for(i=0; i<r1; ++i)
        for(j=0; j<c2; ++j)
        {
            result[i][j] = 0;
        }
 
             // Multiplying matrices a and b and
            // storing result in result matrix
            for(i=0; i<r1; ++i)
            for(j=0; j<c2; ++j)
            for(k=0; k<c1; ++k)
            {
                result[i][j]+=a[i][k]*b[k][j];
            }
 
        // Displaying the result
        cout<<"\nOutput Matrix:\n";
        for(i=0; i<r1; ++i)
        for(j=0; j<c2; ++j)
        {
            cout<<" "<<result[i][j];
                  if(j == c2-1)
            cout<<"\n\n";
        }
        return 0;
}

Result

Write C++ Program to Multiply Two Matrices
Write C++ Program to Multiply Two Matrices

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