wprintf warning

[Jim Marshall]

Hello,
 I'm sure this has been asked before, but UI can not find the answer via 
searching this list or on google. I'm testing out the use of wchar.h for 
a project I'm working on, I wrote a simple "Hello World" program, but it 
gives me a warning when it is compiled with -Wall:

/* wprint_test.c */
#include <stdio.h>
#include <wchar.h>

int main(int argc, char** argv) {
  wprintf(L"Hello World\n");
  return 0;
}

When I compile this with -Wall I get:

cc -Wall wprint_test.c
wprint_test.c: In function 'main':
wprint_test.c:5: warning: implicit declaration of function 'wprintf'

what do I need to do to compile with -Wall and not get this warning (I 
have tried adding -D__USE_ISOC99 and -D__USE_UNIX98). Is it possible?

Using gcc 3.2 20020903 (Red Hat Linux 8.0 3.2-7)

Thank you