c-plus-plus-code-solutions/17.4 (C++) Sum of the diagonal elements of a 2D array.cpp at main · msa-iqbal/c-plus-plus-code-solutions · GitHub

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/// Sum of the diagonal elements of a 2D array
/*
Explain:
        Matrix (A):
        -----------------------------
                      col[0]  | col[1] | col[2]
                    ------------------------
        Row[0]   |   1     |     2    |   3
                    ------------------------
        Row[1]   |   4     |     5    |   6
                    ------------------------
        Row[2]   |   7     |     8    |   9

        Example:
                        Diagonal elements are: 1 5 9
                        Sum of diagonal elements = 1+5+9 = 15
        Calculate:
               - Summation of value where, (row == col) is equal
*/

#include <iostream>
using namespace std;

int main()
{
        int a[50][50];
        int numberOfrows=0, numberOfcols=0;
        int row, col, r=0, sum=0;

        // Input the total numbers of row and columns
        cout<<" Enter the total numbers of row & column for create a matrix: \n";
        cout<<" Enter the total row of the matrix: ";
        cin>>numberOfrows;
        cout<<" Enter the total col of the matrix: ";
        cin>>numberOfcols;

        while(numberOfrows != numberOfcols){
                cout<<"\n\t Error!! Row & Column not equal of the matrix \n\n";

                cout<<" Enter the total numbers of row & column for create a matrix: \n";
                cout<<" Enter the total row of the matrix: ";
                cin>>numberOfrows;
                cout<<" Enter the total col of the matrix: ";
                cin>>numberOfcols;
        }

        /* ------------------- Insert the values of A Matrix ------------------- */
        cout<<"\n ------------------- Insert the values of this Matrix: ";
        cout<<"\n Enter the values of row 0: \n";
        for(row=0; row<numberOfrows; row++){                    // Insert the values of A Matrix
                for(col=0; col<numberOfcols; col++){
                        cout<<" a["<<row<<"]["<<col<<"]: ";
                        cin>>a[row][col];
                }
                r++;
                if(r==numberOfrows){
                        cout<<"\n";
                }
                else{
                        cout<<"\n Enter the values of row "<<r<<": ";
                }
                cout<<"\n";
        }

        /*------------------- Print the values of A Matrix ------------------- */
        cout<<"\n ------------------- Print the Values of this Matrix ------------------- \n";
        cout<<" The A Matrix is: \n";
        for(int row=0; row<numberOfrows; row++){          // Print A Matrix
               cout<<"\t\t\t";
                for(int col=0; col<numberOfcols; col++){
                        cout<<a[row][col]<<"  ";
                }
                cout<<"\n";
        }

        /*------------------- Calculate Diagonal Elements of a matrix ------------------- */
        cout<<"\n Diagonal elements are: ";
        for(row=0; row<numberOfrows; row++){                              /// Calculate Diagonal Elements of a matrix
                for(col=0; col<numberOfcols; col++){
                        if(row==col){
                             cout<<a[row][col]<<" ";
                             sum=sum + a[row][col];
                        }
                }
        }
        cout<<"\n Sum of diagonal elements = "<<sum<<" \n";

        return 0;
}

/* ===== Output / Result:
 Input:
 ------------------------------------------------------------------
 Enter the total numbers of row & column for create a matrix:
 Enter the total row of the matrix: 1
 Enter the total col of the matrix: 3
         Error!! Row & Column not equal of the matrix

 Enter the total numbers of row & column for create a matrix:
 Enter the total row of the matrix: 3
 Enter the total col of the matrix: 3

 Insert the values of this Matrix:
 Enter the values of row 0:
 a[0][0]: 11
 a[0][1]: 12
 a[0][2]: 13

 Enter the values of row 1:
 a[1][0]: 14
 a[1][1]: 15
 a[1][2]: 16

 Enter the values of row 2:
 a[2][0]: 17
 a[2][1]: 18
 a[2][2]: 19


 Output:
 --------------------------------------
 The A Matrix is:
                        11  12  13
                        14  15  16
                        17  18  19

 Diagonal elements are: 11 15 19
 Sum of diagonal elements = 45
*/