C++ program to calculate sum of diagonal elements of given matrix.

 #include<iostream.h>

#include<conio.h>

#define r 3

#define c 3

void main(){

int A[r][c],i,j,sum=0;

clrscr();

cout<<"Enter Elements of Matrix A"<<endl;

for(i=0;i<r;i++){

for(j=0;j<c;j++){

cout<<"A["<<i<<"]"<<"["<<j<<"]=";

cin>>A[i][j];

if(i==j) 

sum=sum+A[i][j];

}}

cout<<"Sum of diagonal elements of Matrix A is = "<<sum<<endl;

getch();

}