C Program to Find Sum of Diagonal Elements of a Matrix

This is a program to do the sum of the main & opposite diagonal elements of a MxN Matrix

Problem Description

This C Program finds the sum of the main & opposite diagonal elements of a MxN Matrix. The program accepts an MxN matrix. Then adds main diagonal of matrix as well as the opposite diagonal of the matrix.

Problem Solution

1. Create a matrix and define its elements.
2. Declare two variables which will store sum of main and opposite diagonal.
3. Now run a single for loop and extract main diagonals elements adding to the first variable and opposite diagonal elements to the second variable.

Program/Source Code

Here is source code of the C program to finds the sum of the main & opposite diagonal elements of a MxN Matrix. The program is successfully compiled and tested using Turbo C compiler in windows environment. The program output is also shown below.

```
    /*
```

     * C program to find accept a matrix of order M x N and find

     * the sum of the  main diagonal and off diagonal elements

```
     */
```
```
 
```
```
    #include <stdio.h>
```
```
    void main ()
```
```
    {
```
```
 
```
```
        static int array[10][10];
```
```
        int i, j, m, n, a = 0, sum = 0;
```
```
 
```

        printf("Enetr the order of the matix \n");

```
        scanf("%d %d", &m, &n);
```
```
 
```
```
        if (m == n ) 
```
```
        {
```
```
 
```

            printf("Enter the co-efficients of the matrix\n");

```
            for (i = 0; i < m; ++i)
```
```
            {
```
```
                for (j = 0; j < n; ++j)
```
```
                {
```

                    scanf("%d", &array[i][j]);

```
                }
```
```
            }
```
```
 
```

            printf("The given matrix is \n");

```
            for (i = 0; i < m; ++i) 
```
```
            {
```
```
                for (j = 0; j < n; ++j)
```
```
                {
```

                    printf(" %d", array[i][j]);

```
                }
```
```
                printf("\n");
```
```
            }
```
```
 
```
```
            for (i = 0; i < m; ++i) 
```
```
            {
```

                sum = sum + array[i][i];

                a = a + array[i][m - i - 1];

```
            }
```
```
 
```

            printf("\nThe sum of the main diagonal elements is = %d\n", sum);

            printf("The sum of the off diagonal elements is   = %d\n", a);

```
 
```
```
        }
```
```
 
```
```
        else
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            printf("The given order is not square matrix\n");

```
 
```
```
    }
```

Program Explanation

1. Declare a matrix, taking order as input from users and define all its elements.
2. Declare two variable to store sum of each diagonal elements.
3. Run a for loop wherein the main diagonal element is given by index (i, i) where i is the iterator and opposite diagonal element is given by index(i, total_rows(m)-i-1).
4. The two variables are initialized to 0, which are summed up by diagonal elements.
5. Print the sum of diagonal elements.

Runtime Test Cases

Enter the order of the matix
2 2
Enter the co-efficients of the matrix
40 30
38 90
The given matrix is
 40 30
 38 90
 
The sum of the main diagonal elements is = 130
The sum of the off diagonal elements is   = 68

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