NULL, NUL, EOF, '/0'区别
2014-08-15 13:54
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NULL, NUL, EOF, '/0'区别
分类: linux操作系统 c语言2011-05-1714:32 342人阅读 评论(1) 收藏 举报
nullcharacterpointerscompilerintegereach
NULL: 定义为0或0L或(void *)0,用于指示一个指针值是空,即什么都不指;
'/0': 用且只用字符串结束符;
NUL : 0x00,0值字符,可以用于结束ASCII字符串,和'/0'类似,但是在c/c++中没有定义,如果要使用的话,需要自定义为 #define NUL '/0';
EOF :通常定义为-1, 文件结束符标志,一般是ctrl+z.
NULL is a macro defined in several standard headers, 0 is an integer constant, '/0' is a character constant, and nul is the name of the character constant. All of these are *not* interchangeable:
NULL is to be used for pointers only since it may be defined as ((void *)0), this would cause problems with anything but pointers.
0 can be used anywhere, it is the generic symbol for each type's zero value and the compiler will sort things out.
'/0' should be used only in a character context.
nul is not defined in C or C++, it shouldn't be used unless you define it yourself in a suitable manner, like:
#define nul '/0'
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