Reverse diagonals of matrix

Posted on Apr 26, 2020

C program to reverse diagonal elements of matrix.

Program

#include<stdio.h>
#include<conio.h>
#define MAX 10

void read_matrix(int mat[MAX][MAX], int row, int col)
{
    int i, j;
    for(i=0;i<row;i++)
    {
        for(j=0;j<col;j++)
        {
            printf("Element [%d][%d]\t:",i,j);
            scanf("%d",&mat[i][j]);
        }
    }
}

void print_matrix(int mat[MAX][MAX], int row, int col)
{
    int i, j;
    for(i=0;i<row;i++)
    {
        for(j=0;j<col;j++)
        {
            printf("%d\t",mat[i][j]);
        }
        printf("\n");
    }
}

void rev_diag(int mat[MAX][MAX], int row, int col)
{
    int i, j, temp;

    i = 0;
    j = row;
    while(i<j)
    {
        temp = mat[i][i];
        mat[i][i] = mat[j-1][j-1];
        mat[j-1][j-1] = temp;

        temp = mat[i][j-1];
        mat[i][j-1] = mat[j-1][i];
        mat[j-1][i] = temp;

        i++;
        j--;
    }
}

void main()
{
    int mat[MAX][MAX];
    int row, col;

    printf("Enter the number of rows or columns of the square matrix\t:");
    scanf("%d",&row);
    col = row;

    printf("Enter the elements of the matrix\n");
    read_matrix(mat, row, col);

    printf("\nMatrix entered is\n");
    print_matrix(mat, row, col);

    rev_diag(mat, row, col);

    printf("\nMatrix after reversing the diagonals\n");
    print_matrix(mat, row, col);

    getch();
}

Output

Enter the number of rows or columns of the square matrix        :4
Enter the elements of the matrix
Element [0][0]  :1
Element [0][1]  :2
Element [0][2]  :3
Element [0][3]  :4
Element [1][0]  :5
Element [1][1]  :6
Element [1][2]  :7
Element [1][3]  :8
Element [2][0]  :9
Element [2][1]  :10
Element [2][2]  :11
Element [2][3]  :12
Element [3][0]  :13
Element [3][1]  :14
Element [3][2]  :15
Element [3][3]  :16

Matrix entered is
1       2       3       4
5       6       7       8
9       10      11      12
13      14      15      16

Matrix after reversing the diagonals
16      2       3       13
5       11      10      8
9       7       6       12
4       14      15      1