Is something like this possible in C? It would be really nice to have both of these.

    typedef struct {
        int r;
        char a0[0];
        char a1[0];
    }

CodePudding user response：

No. Rather use dynamically allocated memory. Something like:

typedef struct {
    int *data1;
    size_t len1

    int *data;
    size_t len2;
} sometype;

sometype *alloc_sometype(size_t len1, size_t len2) {
    sometype *n = malloc(sizeof(sometype));

    if (!n) return NULL;

    n->len1 = len1;
    n->len2 = len2;

    n->data1 = malloc(sizeof(int) * len1);
    n->data2 = malloc(sizeof(int) * len2);

    // Error handling if those malloc calls fail

    return n;
}

CodePudding user response：

The flexible array must be the last member in the struct. However, if both arrays are supposed to have the same size, you could combine them:

#include <stdio.h>
#include <stdlib.h>

typedef struct { // a struct to keep one a0 a1 pair
    char a0;
    char a1;
} A;

typedef struct {
    int len;
    A a[];        // flexible array of a0 a1 pairs
} data;

data *data_create(size_t len) {
    data *d = malloc(sizeof *d   len * sizeof *d->a);
    if(d) d->len = len;
}

int main() {
    data *d = data_create(10);

    for(size_t i = 0; i < d->len;   i) {
        d->a[i].a0 = i;
        d->a[i].a1 = i 1;
    }
    
    free(d);
}