gcc-you can use this code to learn something about gcc, and inquire further into linux,
源代码在线查看： if-1.c
/* { dg-do preprocess } */ /* { dg-options "-pedantic-errors" } */ #if 0xa != 10 #error 0xa != 10 /* { dg-bogus "#error" "normal conversion" } */ #endif #if 077 != 63 #error 077 != 63 /* { dg-bogus "#error" "normal conversion" } */ #endif #if 12wrt /* { dg-error "invalid suffix" "invalid number" } */ #endif #if 0abc /* { dg-error "invalid suffix" "invalid number" } */ #endif #if 42abc /* { dg-error "invalid suffix" "invalid number" } */ #endif #if 0xabc != 2748 #error 0xabc /* { dg-bogus "#error" "normal conversion" } */ #endif #if 1.2 /* { dg-error "loating constant" "floating point in #if" } */ #endif #if 4uu /* { dg-error "invalid suffix" "too many suffixes" } */ #endif #if 124123231lll /* { dg-error "invalid suffix" "too many suffixes" } */ #endif #if 1234lul /* { dg-error "invalid suffix" "u between ls" } */ #endif #if 099 /* { dg-error "invalid digit" "decimal in octal constant" } */ #endif #if 0xfffffffffffffffff /* { dg-error "integer constant" "range error" } */ #endif
