Ownership

An ownership convention decides which function is responsible for freeing heap storage.

ownership.c

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

int *makeValue(int value) {
    int *ptr = (int *)malloc(sizeof(int));
    if (ptr != 0) {
        *ptr = value;
    }
    return ptr;
}

int consumeValue(int *owned) {
    int result = *owned;
    free(owned);
    return result;
}

int main(void) {
    int value = ;
    int *owned = makeValue(value);

    if (owned == 0) {
        return 1;
    }

    int result = consumeValue(owned);
    owned = 0;

    printf("result=%d owned=%d\n", result, owned == 0);
    return 0;
}

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

int *makeValue(int value) {
    int *ptr = (int *)malloc(sizeof(int));
    if (ptr != 0) {
        *ptr = value;
    }
    return ptr;
}

int consumeValue(int *owned) {
    int result = *owned;
    free(owned);
    return result;
}

int main(void) {
    int value = ;
    int *owned = makeValue(value);

    if (owned == 0) {
        return 1;
    }

    int result = consumeValue(owned);
    owned = 0;

    printf("result=%d owned=%d\n", result, owned == 0);
    return 0;
}

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

int *makeValue(int value) {
    int *ptr = (int *)malloc(sizeof(int));
    if (ptr != 0) {
        *ptr = value;
    }
    return ptr;
}

int consumeValue(int *owned) {
    int result = *owned;
    free(owned);
    return result;
}

int main(void) {
    int value = ;
    int *owned = makeValue(value);

    if (owned == 0) {
        return 1;
    }

    int result = consumeValue(owned);
    owned = 0;

    printf("result=%d owned=%d\n", result, owned == 0);
    return 0;
}

owner The owner of a heap pointer is responsible for calling `free`.

transfer Passing a pointer to a consuming function can transfer that responsibility.