Question

How to print the boundary elements of a matrix in C

Answer 1

#include <stdio.h>  

#define COLS 5

void printMatrixBoundaries(int matrix[][COLS], int rows, int cols) {
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            if (i == 0 || j == 0 || i == rows - 1 || j == cols - 1) {
                printf("%d ", matrix[i][j]);
            }
        }
    }
}

int main() {
    int matrix[][COLS] = { { 1,  2,  3,  4,  5},
                           { 6,  7,  8,  9, 10},
                           {11, 12, 13, 14, 15},
                           {16, 17, 18, 19, 20} };

    int rows = sizeof matrix / sizeof matrix[0];
    int cols = sizeof matrix[0] / sizeof(int);

    printMatrixBoundaries(matrix, rows, cols);

    return 0;
}




/*
run:

1 2 3 4 5 6 10 11 15 16 17 18 19 20

*/

 

70+ SQL courses for beginners and professionals

Answer 2

#include <stdio.h>  

#define COLS 5

void printMatrixBoundaries(int matrix[][COLS], int rows, int cols) {
    for (int j = 0; j < cols; j++) {
        printf("%d ", matrix[0][j]);
    }

    for (int j = 0; j < cols; j++) {
        if (j == cols - 1) {
            for (int i = 1; i < rows; i++) {
                printf("%d ", matrix[i][j]);
            }
        }
    }

    for (int j = cols - 2; j > -1; j--) {
        printf("%d ", matrix[rows - 1][j]);
    }

    for (int i = rows - 2; i > 0; i--) {
        printf("%d ", matrix[i][0]);
    }
}

int main() {
    int matrix[][COLS] = { { 1,  2,  3,  4,  5},
                           { 6,  7,  8,  9, 10},
                           {11, 12, 13, 14, 15},
                           {16, 17, 18, 19, 20} };

    int rows = sizeof matrix / sizeof matrix[0];
    int cols = sizeof matrix[0] / sizeof(int);

    printMatrixBoundaries(matrix, rows, cols);

    return 0;
}




/*
run:

1 2 3 4 5 10 15 20 19 18 17 16 11 6

*/

 

70+ SQL courses for beginners and professionals