C Exercises: Find sum of right diagonals of a matrix

Last update on July 31 2025 13:03:49 (UTC/GMT +8 hours)

23. Right Diagonal Sum

Write a program in C to find the sum of the right diagonals of a matrix.

The task is to write a C program that calculates the sum of the elements along the right diagonal of a square matrix. The program prompts the user to input the size of the matrix and its elements, computes the sum of the elements from the top-right to bottom-left diagonal, and displays both the matrix and the sum of its right diagonal elements as output.

Visual Presentation:

C Exercises: Find sum of right diagonals of a matrix

Sample Solution:

C Code:

#include <stdio.h>

int main() {
    // Declare variables and matrix
    int i, j, arr1[50][50], sum = 0, n;

    // Display the purpose of the program
    printf("\n\nFind sum of right diagonals of a matrix :\n");
    printf("---------------------------------------\n");

    // Input the size of the square matrix
    printf("Input the size of the square matrix : ");
    scanf("%d", &n);

    // Input elements into the matrix and calculate sum of right diagonals
    printf("Input elements in the matrix :\n");
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            printf("element - [%d],[%d] : ", i, j);
            scanf("%d", &arr1[i][j]);
            // Calculate sum of elements on the right diagonal
            if (i == j) {
                sum = sum + arr1[i][j];
            }
        }
    }

    // Display the matrix
    printf("The matrix is :\n");
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            printf("% 4d", arr1[i][j]);
        }
        printf("\n");
    }

    // Display the sum of right diagonal elements
    printf("Addition of the right Diagonal elements is : %d\n", sum);

    return 0;
}

Sample Output:

Find sum of right diagonals of a matrix :                                                                     
---------------------------------------                                                                       
Input the size of the square matrix : 2                                                                       
Input elements in the first matrix :                                                                          
element - [0],[0] : 1                                                                                         
element - [0],[1] : 2                                                                                         
element - [1],[0] : 3                                                                                         
element - [1],[1] : 4                                                                                         
The matrix is :                                                                                               
   1   2                                                                                                      
   3   4                                                                                                      
Addition of the right Diagonal elements is :5

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to compute the sum of the primary diagonal elements of a matrix.
Write a C program to display the elements on the right diagonal of a matrix and then compute their product.
Write a C program to compute the right diagonal sum of a matrix using recursion.
Write a C program to compute both the primary and secondary diagonal sums and compare them.

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