limits.h文件中规定了是IDE在OS中规定了每个数据类型的最大值和最小值以及在程序源代码中编译时候所占用的字节数，这这样做有利于帮助程序员在编写程序的时候有效控制在选择合适数据类型的显示范围值。
/***
*limits.h - implementation dependent values
*
* Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
* Contains defines for a number of implementation dependent values
* which are commonly used in C programs.
* [ANSI]
*
* [Public]
*
****/ #pragma once #include <crtdefs.h> #ifndef _INC_LIMITS
#define _INC_LIMITS #define CHAR_BIT 8 /* number of bits in a char. int，shor，long等类型在标准中，默认类型位signed类型，但是char类型在标准中默认为unsigned类型。*/
#define SCHAR_MIN (-128) /* minimum signed char value */
#define SCHAR_MAX 127 /* maximum signed char value */
#define UCHAR_MAX 0xff /* maximum unsigned char value */ #ifndef _CHAR_UNSIGNED
#define CHAR_MIN SCHAR_MIN /* mimimum char value */
#define CHAR_MAX SCHAR_MAX /* maximum char value */
#else
#define CHAR_MIN 0 /**/
#define CHAR_MAX UCHAR_MAX
#endif /* _CHAR_UNSIGNED */ #define MB_LEN_MAX 5 /* max. # bytes in multibyte char */
#define SHRT_MIN (-32768) /* minimum (signed) short value */
#define SHRT_MAX 32767 /* maximum (signed) short value */
#define USHRT_MAX 0xffff /* maximum unsigned short value */
#define INT_MIN (-2147483647 - 1) /* minimum (signed) int value */
#define INT_MAX 2147483647 /* maximum (signed) int value */
#define UINT_MAX 0xffffffff /* maximum unsigned int value */
#define LONG_MIN (-2147483647L - 1) /* minimum (signed) long value */
#define LONG_MAX 2147483647L /* maximum (signed) long value */
#define ULONG_MAX 0xffffffffUL /* maximum unsigned long value */
#define LLONG_MAX 9223372036854775807i64 /* maximum signed long long int value */
#define LLONG_MIN (-9223372036854775807i64 - 1) /* minimum signed long long int value */
#define ULLONG_MAX 0xffffffffffffffffui64 /* maximum unsigned long long int value */ #define _I8_MIN (-127i8 - 1) /* minimum signed 8 bit value */
#define _I8_MAX 127i8 /* maximum signed 8 bit value */
#define _UI8_MAX 0xffui8 /* maximum unsigned 8 bit value */ #define _I16_MIN (-32767i16 - 1) /* minimum signed 16 bit value */
#define _I16_MAX 32767i16 /* maximum signed 16 bit value */
#define _UI16_MAX 0xffffui16 /* maximum unsigned 16 bit value */ #define _I32_MIN (-2147483647i32 - 1) /* minimum signed 32 bit value */
#define _I32_MAX 2147483647i32 /* maximum signed 32 bit value */
#define _UI32_MAX 0xffffffffui32 /* maximum unsigned 32 bit value */ /* minimum signed 64 bit value */
#define _I64_MIN (-9223372036854775807i64 - 1)
/* maximum signed 64 bit value */
#define _I64_MAX 9223372036854775807i64
/* maximum unsigned 64 bit value */
#define _UI64_MAX 0xffffffffffffffffui64 #if _INTEGRAL_MAX_BITS >= 128
/* minimum signed 128 bit value */
#define _I128_MIN (-170141183460469231731687303715884105727i128 - 1)
/* maximum signed 128 bit value */
#define _I128_MAX 170141183460469231731687303715884105727i128
/* maximum unsigned 128 bit value */
#define _UI128_MAX 0xffffffffffffffffffffffffffffffffui128
#endif #ifndef SIZE_MAX
#ifdef _WIN64
#define SIZE_MAX _UI64_MAX
#else
#define SIZE_MAX UINT_MAX
#endif
#endif #if __STDC_WANT_SECURE_LIB__
/* While waiting to the C standard committee to finalize the decision on RSIZE_MAX and rsize_t,
* we define RSIZE_MAX as SIZE_MAX
*/
#ifndef RSIZE_MAX
#define RSIZE_MAX SIZE_MAX
#endif
#endif #ifdef _POSIX_ #define _POSIX_ARG_MAX 4096
#define _POSIX_CHILD_MAX 6
#define _POSIX_LINK_MAX 8
#define _POSIX_MAX_CANON 255
#define _POSIX_MAX_INPUT 255
#define _POSIX_NAME_MAX 14
#define _POSIX_NGROUPS_MAX 0
#define _POSIX_OPEN_MAX 16
#define _POSIX_PATH_MAX 255
#define _POSIX_PIPE_BUF 512
#define _POSIX_SSIZE_MAX 32767
#define _POSIX_STREAM_MAX 8
#define _POSIX_TZNAME_MAX 3 #define ARG_MAX 14500 /* 16k heap, minus overhead */
#define LINK_MAX 1024
#define MAX_CANON _POSIX_MAX_CANON
#define MAX_INPUT _POSIX_MAX_INPUT
#define NAME_MAX 255
#define NGROUPS_MAX 16
#define OPEN_MAX 32
#define PATH_MAX 512
#define PIPE_BUF _POSIX_PIPE_BUF
#define SSIZE_MAX _POSIX_SSIZE_MAX
#define STREAM_MAX 20
#define TZNAME_MAX 10 #endif /* POSIX */ #endif /* _INC_LIMITS */