[Solved] In c program, why free memory of string (which copy from strcpy) in osx is not woking? [duplicate]

Question

Your problem is your placement of free(copy), move it after you make use of copy, otherwise you are attempting to read from a variable that has already been freed (an uninitialized value – invoking Undefined Behavior), (as @Pras correctly notes you free (copy), not free (origin), e.g.

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

int main(){
    char *copy;
    char *origin = "tutorialspoint";
    copy = malloc (strlen (origin) + 1);
    strcpy(copy, origin);

    printf("string = %s,  Address = %p\n", copy, (void *)copy);
    printf("origin = %s,  Address = %p\n", origin, (void *)origin);
    free(copy);  /* works find here */
    return(0);
}

note: use of %p for the pointer address.

You should also validate ALL memory allocations, e.g.

    if (!(copy = malloc (strlen (origin) + 1))) {
        fprintf (stderr, "error: virtual memory exhausted.\n");
        return 1;
    }

Example Use/Output

$ ./bin/origin
string = tutorialspoint,  Address = 0xbe3010
origin = tutorialspoint,  Address = 0x400710

copy is freed

Continuing from your comment, copy is in fact freed. How can you tell? You run you code through a memory/error checking program like valgrind, e.g.

$ valgrind ./bin/origin
==10564== Memcheck, a memory error detector
==10564== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==10564== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==10564== Command: ./bin/origin
==10564==
string = tutorialspoint,  Address = 0x51d8040
origin = tutorialspoint,  Address = 0x400710
==10564==
==10564== HEAP SUMMARY:
==10564==     in use at exit: 0 bytes in 0 blocks
==10564==   total heap usage: 1 allocs, 1 frees, 15 bytes allocated
==10564==
==10564== All heap blocks were freed -- no leaks are possible
==10564==
==10564== For counts of detected and suppressed errors, rerun with: -v
==10564== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

As you can see, all memory allocated had in fact been freed and — no leaks are possible and there were 0 errors from 0 contexts.

Accepted Answer