limits.h【limits.h】limits.h专门用于检测整型数据数据类型的表达值範围 。
基本介绍中文名：极限头档案
外文名：<limits.h>或<climits>
用途：检测整型数据数据类型表达值範围
判断类型：可以容纳的最大值或最小值
性质：检测表达值
基本释义limits.h包含内容（包括注释）/** limits.h* This file has no copyright assigned and is placed in the Public Domain.* This file is a part of the mingw-runtime package.* No warranty is given; refer to the file DISCLAIMER within the package.** Functions for manipulating paths and directories (included from io.h)* plus functions for setting the current drive.** Defines constants for the sizes of integral types.** NOTE: GCC should supply a version of this header and it should be safe to* use that version instead of this one (maybe safer).**/#ifndef _LIMITS_H_#define _LIMITS_H_/* All the headers include this file. */#include <_mingw.h>/** File system limits** TODO: NAME_MAX and OPEN_MAX are file system limits or not? Are they the* same as FILENAME_MAX and FOPEN_MAX from stdio.h?* NOTE: Apparently the actual size of PATH_MAX is 260, but a space is* required for the NUL. TODO: Test?*/#define PATH_MAX (259)/** Characteristics of the char data type.** TODO: Is MB_LEN_MAX correct?*/#define CHAR_BIT 8#define MB_LEN_MAX 2#define SCHAR_MIN (-128)#define SCHAR_MAX 127#define UCHAR_MAX 255/* TODO: Is this safe? I think it might just be testing the preprocessor,* not the compiler itself... */#if ('\x80' < 0)#define CHAR_MIN SCHAR_MIN#define CHAR_MAX SCHAR_MAX#else#define CHAR_MIN 0#define CHAR_MAX UCHAR_MAX#endif/** Maximum and minimum values for ints.*/#define INT_MAX 2147483647#define INT_MIN (-INT_MAX-1)#define UINT_MAX 0xffffffff/** Maximum and minimum values for shorts.*/#define SHRT_MAX 32767#define SHRT_MIN (-SHRT_MAX-1)#define USHRT_MAX 0xffff/** Maximum and minimum values for longs and unsigned longs.** TODO: This is not correct for Alphas, which have 64 bit longs.*/#define LONG_MAX 2147483647L#define LONG_MIN (-LONG_MAX-1)#define ULONG_MAX 0xffffffffUL/** The GNU C compiler also allows 'long long int'*/#if !defined(__STRICT_ANSI__) && defined(__GNUC__)#define LONG_LONG_MAX 9223370L#define LONG_LONG_MIN (-LONG_LONG_MAX-1)#define ULONG_LONG_MAX (2ULL * LONG_LONG_MAX + 1) /* ISO C9x macro names */#define LLONG_MAX LONG_LONG_MAX#define LLONG_MIN LONG_LONG_MIN#define ULLONG_MAX ULONG_LONG_MAX/* MSVC compatibility */#define _I64_MIN LONG_LONG_MIN#define _I64_MAX LONG_LONG_MAX#define _UI64_MAX ULONG_LONG_MAX#endif /* Not Strict ANSI and GNU C compiler */#endif /* not _LIMITS_H_ */补充内容要判断某种特定类型可以容纳的最大值或最小值，一种简便的方法是使用ANSI标準头档案limits.h中的预定义值 。该档案包含一些很有用的常量，它们定义了各种类型所能容纳的值，下表列出了这些常量：常 量 描 述CHAR_BIT char的二进制位数(bit)CHAR_MAX char的有符号整数最大值CHAR_MIN char的有符号整数最小值MB_LEN_MAX 多位元组字元的最大位元组(byte)数INT_MAX int的有符号最大值INT_MIN int的有符号最小值LONG_MAX long的十进制最大值LONG_MIN long的十进制最小值SCHAR_MAX signedchar的十进制整数最大值SCHAR_MIN signedchar的十进制整数最小值SHRT_MIN short的十进制最小值SHRT_MAX short的十进制最大值UCHAR_MAX unsignedchar的十进制整数最大值UINT_MAX unsignedint的十进制最大值ULONG_MAX unsignedlongint的十进制最大值USHRT_MAX unsignedshortint的十进制最大值对于整数类型，在使用2的补码运算的机器(你将使用的机器几乎都属此类)上，一个有符号类型可以容纳的数字範围为[- 2^(位数-1) ]到[+ 2^(位数 -1)-1]，一个无符号类型可以容纳的数字範围为0到(+ 2^位数 ) 。例如，一个16位有符号整数可以容纳的数字範围为-2^15(即-32768)到(+2^15-1)(即+32767) 。而16为无符号整数可容纳的最大值为(2^位数-1)或表示为彙编形式0xffff 。