Makefile

CC = gcc
CC32 = gcc -m32
CC64 = gcc -m64
CFLAGS = -Wall -Wextra -g
CPPFLAGS =
LDFLAGS =
LIBS =
RM = rm -f

TARGETS = sizeof sizeof32 sizeof64

all: $(TARGETS)

clean:
	$(RM) $(TARGETS)

sizeof: sizeof.c
	$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ sizeof.c
sizeof32: sizeof.c
	$(CC32) $(CFLAGS) $(CPPFLAGS) -o $@ sizeof.c
sizeof64: sizeof.c
	$(CC64) $(CFLAGS) $(CPPFLAGS) -o $@ sizeof.c

sizeof.c

#include <inttypes.h>
#include <limits.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
  (void)argc;
  (void)argv;

#ifdef __LP64__
#ifndef PRIuSIZE
  printf("PRIuSIZE not defined\n");
#define PRIuSIZE "lu"
#endif
  printf("__LP64__ defined\n");
#else
#ifndef PRIuSIZE
  printf("PRIuSIZE not defined\n");
#if defined(__APPLE__)
#define PRIuSIZE "lu"
#else
#define PRIuSIZE "u"
#endif
#endif
  printf("__LP64__ not defined\n");
#endif
#define PRINTF_SIZEOF(type) printf("sizeof (" #type ") = %" PRIuSIZE "\n", sizeof (type))

  PRINTF_SIZEOF(int);
  PRINTF_SIZEOF(long);
  PRINTF_SIZEOF(int *);

  return 0;
}