gcc-you can use this code to learn something about gcc, and inquire further into linux,
源代码在线查看： if-mop.c
/* Copyright (C) 2000 Free Software Foundation, Inc. */ /* { dg-do preprocess } */ /* Source: Neil Booth. */ /* Various illegal expressions with missing components. */ #if /* { dg-error "no expression" "empty #if" } */ #endif #if ~ /* { dg-error "no right op" "no unary operand" } */ #endif #if 3 + * 6 + 4 /* { dg-error "no right op" "no right operand" } */ #endif #if 2 ~2 /* { dg-error "missing bin" "no binary operator" } */ #endif #if 1 + 2 (3) /* { dg-error "missing bin" "immediate then open paren" } */ #endif #if (2) 4 * 2 /* { dg-error "missing bin" "close paren then immediate" } */ #endif
