Help with 64 bit malloc

Question

I have read many things but I can't get a simple malloc to work in 64 bit...
cc -xarch=v8 help.c <- will compile and run fine.
cc -xarch=v9a help.c <- will compile and core dump. ( malloc is not returning a valid pointer address )
#include <sys/types.h>
int main( int argc, char *argv[] )
char * help;
help = ( char * ) ( uintptr_t ) malloc( 3 );
help[0] = 'm';
help[1] = 'e';
help[2] = '\0';
(void) printf( "Help %s \n", help );
return 1;
What am I missing ?

Answer 1

Add this line:
#include <stdlib.h>
It will define malloc and let the system know that
malloc will return a pointer. Without that, it will
default to thinking that malloc will return int, which
is 32-bit.