# C program to find the sum of opposite diagonal elements of a matrix

Write a C program to read elements in a matrix and find the sum of minor diagonal (opposite diagonal) elements. C program to calculate sum of minor diagonal elements. Logic to find sum of opposite diagonal elements of a matrix in C programming.

Example

Input

```Input elements in array:
1 2 3
4 5 6
7 8 9```

Output

`Sum of minor diagonal elements = 15`

## Required knowledge

Basic C programming, For loop, Array

### Minor diagonal of a matrix

Minor diagonal of a matrix A is a collection of elements Aij Such that i + j = N + 1. ## Program to find sum of opposite diagonal elements of a matrix

``````/**
* C program to find sum of opposite diagonal elements of a matrix
*/

#include <stdio.h>

#define SIZE 3 // Matrix size

int main()
{
int A[SIZE][SIZE];
int row, col, sum = 0;

/* Input elements in matrix from user */
printf("Enter elements in matrix of size %dx%d: \n");
for(row=0; row<SIZE; row++)
{
for(col=0; col<SIZE; col++)
{
scanf("%d", &A[row][col]);
}
}

/* Find sum of minor diagonal elements */
for(row=0; row<SIZE; row++)
{
for(col=0; col<SIZE; col++)
{
/*
* If it is minor diagonal of matrix
* Minor diagonal: i+j == N + 1
* Since array elements starts from 0 hence i+j == (N + 1)-2
*/
if(row+col == ((SIZE+1)-2))
{
sum += A[row][col];
}
}
}

printf("\nSum of minor diagonal elements = %d", sum);

return 0;
}``````

Output

```Enter elements in matrix of size 3x3:
1 2 3
4 5 6
7 8 9

Sum of minor elements = 15```

Happy coding 😉