Write a C++ Program to Find the Sum of Matrix Diagonal with an example. In this C++ example, we used for loop to iterate matrix rows and adding items of the diagonal items (sum = sum + sumDgnalArr[rows][rows]).
#include<iostream> using namespace std; int main() { int i, j, rows, columns, sum = 0; cout << "\nPlease Enter the rows and Columns = "; cin >> i >> j; int sumDgnalArr[i][j]; cout << "\nPlease Enter the Items\n"; for(rows = 0; rows < i; rows++) { for(columns = 0; columns < i; columns++) { cin >> sumDgnalArr[rows][columns]; } } for(rows = 0; rows < i; rows++) { sum = sum + sumDgnalArr[rows][rows]; } cout << "\nThe Sum of Diagonal Elements = " << sum; return 0; }
Please Enter the rows and Columns = 3 3
Please Enter the Items
10 20 30
40 50 60
70 80 90
The Sum of Diagonal Elements = 150
In this C++ program to calculate the sum of the Matrix Diagonal, we used extra cout statements to show you the iteration number, row, column value, and the total at each iteration.
#include<iostream> using namespace std; int main() { int i, j, rows, columns, sum = 0; cout << "\nPlease Enter Matrix rows and Columns to find Diagonal Sum = "; cin >> i >> j; int sumDgnalArr[i][j]; cout << "\nPlease Enter the Matrix Items\n"; for(rows = 0; rows < i; rows++) { for(columns = 0; columns < i; columns++) { cin >> sumDgnalArr[rows][columns]; } } for(rows = 0; rows < i; rows++) { cout << "\nIteration = " << rows + 1 << ", Row Number = " << rows << " and Sum = " << sum; sum = sum + sumDgnalArr[rows][rows]; cout << "\nsumDgnalArr["<<rows<<"]["<< rows <<"] = " << sumDgnalArr[rows][rows] << " and sum + sumDgnalArr["<<rows<<"]["<<rows <<"] = " << sum << endl; } cout << "\nThe Sum of Diagonal Elements in this Matrix = " << sum; return 0; }

C++ Program to Find Sum of Matrix Diagonal using a While Loop
#include<iostream> using namespace std; int main() { int i, j, rows, columns, sum = 0; cout << "\nPlease Enter rows and Columns = "; cin >> i >> j; int sumDgnalArr[i][j]; cout << "\nPlease Enter the Items\n"; for(rows = 0; rows < i; rows++) { for(columns = 0; columns < i; columns++) { cin >> sumDgnalArr[rows][columns]; } } rows = 0; while(rows < i) { sum = sum + sumDgnalArr[rows][rows]; rows++; } cout << "\nThe Sum of Diagonal Elements = " << sum; return 0; }
Please Enter rows and Columns = 3 3
Please Enter the Items
10 22 33
44 55 66
77 88 99
The Sum of Diagonal Elements = 164