Diagonal sum of matrix

Q. Write a C program to find the sum of diagonal elements in matrix.

Hint: If you have following typical square 3X3 matrix, then diagonal elements will be:

1  2  3

4  5  6

7  8  9

In above 3X3 matrix there are two types diagonal element as:

first diagonal elements are  1, 5, 9 and

second diagonal elements are 3, 5,7

Ans.

/*program to find the sum of diagonal elements of the matrix*/

#include<stdio.h>

#include<conio.h>

#define MAX 5

int main()

{

  int mat[MAX][MAX],row,col;

  int i,j,d1=0,d2=0;

  printf("Enter no. of rows and columns : ");

  scanf("%d%d",&row,&col);

  printf("Enter the elements of matrix:\n");

  if(row==col)

  {

    for(i=0; i<row; i++)

    {

      for(j=0; j<col; j++)

         scanf("%d",&mat[i][j]);

    }

    for(i=0,j=col-1; i<row || j>=0; i++,j--)

    {

       d1=d1+mat[i][i];

       d2=d2+mat[i][j];

    }

    printf("\nThe sum of first diagonal elements : %d",d1);

    printf("\nThe sum of second diagonal elements : %d",d2);

  }

  else

  {

     printf("Rows and columns are not equal!");

     printf("\nTry again!");

  }
  getch();
  return 0;

}

output:-

Enter no. of rows and columns : 3  2

Enter the elements of matrix:

Rows and columns are not equal!

Try again!

Enter no. of rows and columns : 3 3

Enter the elements of matrix:

1  2  3

4  5  6

7  8  9

The sum of first diagonal elements : 15

The sum of second diagonal elements : 15 

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