Allocate a 2d array in C with one dimension fixed

Question

I want to dynamically allocate 1 dimension of a 2D array (the other dimension is given). Does this work:

int NCOLS = 20;

// nrows = user input...

double *a         


        

Answer 1

An example:

#include 
#include 

#define COLS 2

void func(int (**arr)[COLS], int rows)
{
    int i, j;

    *arr = malloc(sizeof(int[COLS]) * rows);
    printf("Insert number: \n"); 
    for(i = 0; i < rows; i++) 
        for(j = 0; j < COLS; j++) 
            scanf("%d", &(*arr)[i][j]);
    for(i = 0; i < rows; i++) 
        for(j = 0; j < COLS; j++) 
            printf("%d\n", (*arr)[i][j]);
}


int main(void)
{ 
    int (*arr)[COLS];

    func(&arr, 2);
    free(arr);
    return 0;
}