ptrlist

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

void *assert_malloc(size_t size)
{
    void *result = malloc(size);
    assert(result);
    return result;
}

void *assert_calloc(size_t size, size_t type_size)
{
    void *result = calloc(size, type_size);
    assert(result);
    return result;
}

struct PtrList{
    void **pointer;
    size_t size;
};

PtrList ptr_list_init(size_t size)
{
    PtrList result = {(void **)assert_calloc(size, sizeof(void *)), size};
    return result;
}

#define ptr_list_add(list_to, type, size) \
((type *)ptr_list_add_(list_to, sizeof(type), size))
void *ptr_list_add_(PtrList *list_to, size_t type_size, size_t size)
{
    assert(list_to->pointer);
    void *result = assert_malloc(size * type_size);
    for(int i = 0; i < list_to->size; ++i)
    {
        if(list_to->pointer[i] == 0)
        {
            list_to->pointer[i] = result;
            goto FOUND_OPEN_SPOT_LABEL;
        }
    }
    assert(0); // No more space on PtrList.
    
    FOUND_OPEN_SPOT_LABEL:;
    return result;
}

void ptr_list_free(PtrList *list_to)
{
    assert(list_to->pointer);
    for(int i = 0; i < list_to->size; ++i)
    {
        if(list_to->pointer[i] != 0)
        {
            free(list_to->pointer[i]);
            list_to->pointer[i] = 0;
        }
    }
    
    list_to->size = 0;
    free(list_to->pointer);
    list_to->pointer = 0;
}

int main() {
    
    // Init PtrList with 3 null pointers
    PtrList some_list = ptr_list_init(3);
    
    // malloc and Add pointer to "PtrList some_list"
    int *b = ptr_list_add(&some_list, int, 13);
    int *c = ptr_list_add(&some_list, int, 13);
    
    // Same pointers
    printf("%i\n", b == some_list.pointer[0]);
    printf("%i\n", c == some_list.pointer[1]);
    
    // Wrong
    printf("%i\n", c == some_list.pointer[0]);
    
    // Free all
    ptr_list_free(&some_list);
    
    return 0;
}