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Double Inclusion, Include Guard and Pragma once

C语言里如果有这么几个文件:

File "grandfather.h"
struct foo { int member; };

File "father.h"
#include "grandfather.h"

File "child.c"
#include "grandfather.h"
#include "father.h"

编译器就会报错，因为foo这个结构体被定义了两次。

通常情况下我们会用include guards来避免这样的重复定义

File "grandfather.h"
#ifndef H_GRANDFATHER
#define H_GRANDFATHER
struct foo {
    int member;
};
#endif

File "father.h"
#include "grandfather.h"

File "child.c"
#include "grandfather.h"
#include "father.h"

posted on 2006-11-20 17:30 Giuliano 阅读(117) 评论(0)  编辑 收藏 引用


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