cpp/CPrimerPlus6E/Ch10/vararr2d.c

//vararr2d.c -- functions using VLAs
#include <stdio.h>
#define ROWS 3
#define COLS 4
int sum2d(int rows, int cols, int ar[rows][cols]);
int main(void)
{
    int i, j;
    int rs = 3;
    int cs = 10;
    int junk[ROWS][COLS] = {
        {2,4,6,8},
        {3,5,7,9},
        {12,10,8,6}
    };
    
    int morejunk[ROWS-1][COLS+2] = {
        {20,30,40,50,60,70},
        {5,6,7,8,9,10}
    };
    
    int varr[rs][cs];  // VLA
    
    for (i = 0; i < rs; i++)
        for (j = 0; j < cs; j++)
            varr[i][j] = i * j + j;
    
    printf("3x5 array\n");
    printf("Sum of all elements = %d\n",
           sum2d(ROWS, COLS, junk));
    
    printf("2x6 array\n");
    printf("Sum of all elements = %d\n",
           sum2d(ROWS-1, COLS+2, morejunk));
    
    printf("3x10 VLA\n");
    printf("Sum of all elements = %d\n",
           sum2d(rs, cs, varr));
    
    return 0;
}

// function with a VLA parameter
int sum2d(int rows, int cols, int ar[rows][cols])
{
    int r;
    int c;
    int tot = 0;
    
    for (r = 0; r < rows; r++)
        for (c = 0; c < cols; c++)
            tot += ar[r][c];
    
    return tot;
}