Question

How to append boundary elements of a matrix to an array in C

Answer 1

#include <stdio.h>  

#define COLS 5

void AppendMatrixBoundariesToArray(int matrix[][COLS], int rows, int cols, int arr[]) {
    int arr_index = 0;

    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) {
                arr[arr_index++] = 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);

    int arr[14] = { 0 };

    AppendMatrixBoundariesToArray(matrix, rows, cols, arr);

    for (int i = 0; i < 14; i++) {
        printf("%d ", arr[i]);
    }

    return 0;
}




/*
run:

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

*/

 

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