C++ Program For Addition of Two Matrices

Given two N x M matrices. Find a N x M matrix as the sum of given matrices each value at the sum of values of corresponding elements of the given two matrices. In this article, we will learn about the addition of two matrices.

Approach

Below is the idea to solve the problem.

1. Iterate over every cell of the matrix (i, j).
2. Add the corresponding values of the two matrices.
3. Store in a single matrix i.e. the resultant matrix.

Algorithm

1. Initialize a resultant matrix res[N][M].
2. Run a for loop for counter i as each row and in each iteration:
   1. Run a for loop for counter j as each column and in each iteration:
      1. Add values of the two matrices for index i, j, and store in res[i][j].
3. Return res.

Below is the Implementation of the above approach:

// C++ program for addition // of two matrices #include <bits/stdc++.h> using namespace std; #define N 4 // This function adds A[][] and B[][], // and stores the result in C[][] void add(int A[][N], int B[][N], int C[][N]) {  int i, j;  for (i = 0; i < N; i++)  for (j = 0; j < N; j++)  C[i][j] = A[i][j] + B[i][j]; } // Driver code int main() {  int A[N][N] = { { 1, 1, 1, 1 },  { 2, 2, 2, 2 },  { 3, 3, 3, 3 },  { 4, 4, 4, 4 } };  int B[N][N] = { { 1, 1, 1, 1 },  { 2, 2, 2, 2 },  { 3, 3, 3, 3 },  { 4, 4, 4, 4 } };  // To store the result  int C[N][N];  int i, j;  add(A, B, C);  cout << "Result matrix is " << endl;  for (i = 0; i < N; i++) {  for (j = 0; j < N; j++)  cout << C[i][j] << " ";  cout << endl;  }  return 0; } 

Result matrix is 2 2 2 2 4 4 4 4 6 6 6 6 8 8 8 8 

The complexity of the above method

Time Complexity: O(n²). 

Auxiliary Space: O(n²)

The program can be extended for rectangular matrices. The following post can be useful for extending this program: How to pass a 2D array as a parameter in C?