如何在compiler程式時檢查GCC版本?利用gcc的preprocessor

有些程式想要保證要被某版本以上gcc才能被編譯
寫在程式中 不是寫在configure檔

利用gcc前置處理器preprocessor
看參數 __GNUC__ , __GNUC_MINOR__ , GNU_PATCHLEVEL__

範例如下
hello.c
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#include

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

// Check GCC version (>=2.9.x)
#if ( __GNUC__ >= 3 ) \
|| ( __GNUC__ >= 2 && __GNUC_MINOR__ >= 9 )
#warning "Your GCC is good( need >=2.9.x )"
#else
#error "Your GCC Version is wrong( need >=2.9 )"
#endif

//show GCC version
printf("You are using GCC:%d.%d.%d\n", __GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__);

return 0;
}

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gcc -o hello hello.c