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

#define log_int(n) printf("%s == %d\n", #n, (n))
#define log_addr(n) printf("%s == %p\n", #n, (void*)(n))

// it is the callers responsibility to free the returned address
int* malloc_and_fill_integer(int value) {
    int* a_value = malloc(sizeof(*a_value));
    *a_value = value;
    // pitfall: do not free an address that you will return from the function
    //free(a_value);
    return a_value;
}

int main(int argc, char* argv[]) {
    int* a_num1 = malloc_and_fill_integer(7);
    log_int(*a_num1);
    log_addr(a_num1);

    free(a_num1);
    a_num1 = NULL;

    int* a_num2 = malloc_and_fill_integer(10);
    log_int(*a_num2);
    log_addr(a_num2);

    free(a_num1);
    free(a_num2);
    // invalid free: double free
    return EXIT_SUCCESS;
}
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