pointer_via_string.c

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

int main(int argc, char *argv[], char *env[]) {
    char *arena;
    char hex[100];
    char *target;

    arena = malloc(1024);
    strcpy(arena, "Hello world.\n");
    sprintf(hex, "%lx\n", (intptr_t) arena);
    /* in the real world example, the monstrosity in hex is passed to
       a different function which has responsibility for sscanf()ing and
       free()ing it */

    sscanf(hex, "%lx", (intptr_t *) &target);
    printf("%p\n%s\n", target, target);
    free(target);
    return 0;
}