981001-4.c

来自「this is a gcc file, you can download it 」· C语言 代码 · 共 15 行

#define P(a,b) P1(a,b)
#define P1(a,b) a##b

#define ONCE(x, y) (x ?: (x = y()))
#define PREFIX

extern int P(PREFIX, init) (void);

int
fun(void)
{
  static int memo;
  return ONCE(memo, P(PREFIX, init));
}