Given a matrix, and we have to interchange the specified columns using C program.

Program:

The source code to interchange the columns in the matrix is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.

// C program to interchange the columns in matrix

#include <stdio.h>

int main()
{
    int Matrix[3][3] = {
        { 1, 2, 3 },
        { 4, 5, 6 },
        { 7, 8, 9 }
    };

    int i, j, n1, n2, temp;

    printf("Matrix before column exchange:\n");
    for (i = 0; i < 3; ++i) {
        for (j = 0; j < 3; ++j)
            printf(" %d", Matrix[i][j]);
        printf("\n");
    }

    printf("Enter two column numbers to be exchanged:");
    scanf("%d %d", &n1, &n2);

    //Exchange columns
    for (i = 0; i < 3; ++i) {
        temp = Matrix[i][n1 - 1];
        Matrix[i][n1 - 1] = Matrix[i][n2 - 1];
        Matrix[i][n2 - 1] = temp;
    }

    printf("Matrix after column exchange:\n");
    for (i = 0; i < 3; ++i) {
        for (j = 0; j < 3; ++j)
            printf(" %d", Matrix[i][j]);
        printf("\n");
    }

    return 0;
}

Output:

RUN 1:
Matrix before column exchange:
 1 2 3
 4 5 6
 7 8 9
Enter two column numbers to be exchanged:1 3
Matrix after column exchange:
 3 2 1
 6 5 4
 9 8 7

RUN 2:
Matrix before column exchange:
 1 2 3
 4 5 6
 7 8 9
Enter two column numbers to be exchanged:1 2
Matrix after column exchange:
 2 1 3
 5 4 6
 8 7 9

RUN 3:
Matrix before column exchange:
 1 2 3
 4 5 6
 7 8 9
Enter two column numbers to be exchanged:2 3
Matrix after column exchange:
 1 3 2
 4 6 5
 7 9 8

Explanation:

In the main() function, we created a 3X3 matrix matrix using the 2D array. Then we read column numbers to be exchanged. After that, we interchanged the columns and printed the updated matrix on the console screen.