Add two matrix

In this example we will show you how to add two matrix

#include <iostream>
using namespace std;
#define N 4

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];
        }
    }
}

int main(){
    int arr1[N][N] = {{1,1,1,1},
                      {2,2,2,2},
                      {3,3,3,3}};
    int arr2[N][N] = {{3,3,3,3},
                      {2,2,2,2},
                      {1,1,1,1}};
    
    int arr3[N][N],i,j;
    add(arr1,arr2,arr3);
    cout<<"print add Array"<<endl;
    for(i = 0; i < N; i++){
        for(j = 0; j < N; j++)
        {
            cout<<arr3[i][j]<<" ";
            
        }
        cout<<endl;
    }
    return 0;
}

Output:

4 4 4 4
4 4 4 4
4 4 4 4
0 0 0 0

Explanation:

Step 1: Define a Constant N

• The macro #define N 4 is used to define the size of the matrix (i.e., 4×4). This means the matrix will have 4 rows and 4 columns.

#define N 4

Step 2: Matrix Addition Function

• The function add takes three 2D arrays (A, B, and C) as input. It adds corresponding elements from matrix A and B, then stores the result in matrix 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];  // Adding corresponding elements
        }
    }
}

• Two for loops are used to iterate through all the elements in the 4×4 matrices.
• The values at position [i][j] in both matrices A and B are added together and stored in matrix C.

Step 3: Main Function

• The main() function initializes two 4×4 matrices arr1 and arr2 with hardcoded values. An empty matrix arr3 is also declared to store the result of the addition.

int main() {
    int arr1[N][N] = {{1,1,1,1},
                      {2,2,2,2},
                      {3,3,3,3}};  // Matrix A
                      
    int arr2[N][N] = {{3,3,3,3},
                      {2,2,2,2},
                      {1,1,1,1}};  // Matrix B
    
    int arr3[N][N], i, j;  // Matrix C for storing the result

• Here, only three rows are initialized in arr1 and arr2, but the matrices are declared as 4×4 (N=4). The uninitialized rows will contain garbage values or zeros depending on the compiler’s behavior.

Step 4: Calling the Addition Function

• The function add(arr1, arr2, arr3) is called to perform the matrix addition. This will populate matrix arr3 with the sum of corresponding elements from arr1 and arr2.

    add(arr1, arr2, arr3);  // Call the function to add matrices

Step 5. Print the Resulting Matrix

• The code then prints the result of the matrix addition stored in arr3 using another set of nested loops.

    cout << "print add Array" << endl;
    for (i = 0; i < N; i++) {
        for (j = 0; j < N; j++) {
            cout << arr3[i][j] << " ";  // Print each element in matrix C
        }
        cout << endl;  // Move to the next row after printing one row
    }
    return 0;
}