有关stdint.h 文件

Google C++编程规范的P25页有如下叙述：

<stdint.h> 定义了 int16_t 、 uint32_t 、 int64_t 等整型，在需要确定大小的整型时可以使用它们代替 short 、 unsigned long long 等，在 C 整型中，只使用 int 。适当情况下，推 荐使用标准类型如 size_t 和 ptrdiff_t 。

最常使用的是，对整数来说，通常不会用到太大，如循环计数等，可以使用普通的 int 。 你可以认为 int 至少为 32 位，但不要认为它会多于 32 位，需要 64 位整型的话，可以使用int64_t 或 uint64_t 。对于大整数，使用 int64_t 。

不要使用 uint32_t 等无符号整型，除非你是在表示一个 位组（ bit pattern ） 而不是一个 数值。即使数值不会为负值也不要使用无符号类型，使用断言来保护数据。

有些人，包括一些教科书作者，推荐使用无符号类型表示非负数，类型表明了数值取值形 式 。但是，在 C 语言中，这一优点被由其导致的 bugs 所淹没。看看：

for (unsigned int i = foo.Length()-1; i >= 0; --i) 
上述代码永远不会终止！有时 gcc 会发现该 bug 并报警，但通常不会。类似的 bug 还会 出现在比较有符合变量和无符号变量时，主要是 C 的 类型提升机制（ type-promotion
scheme ， C 语言中各种内建类型之间的提升转换关系） 会致使无符号类型的行为出乎你 的意料。因此，使用断言声明变量为非负数，不要使用无符号型。

以下内容转载自http://apps.hi.baidu.com/share/detail/32935657

按照posix标准，一般整型对应的*_t类型为：1字节     uint8_t2字节     uint16_t4字节     uint32_t8字节     uint64_t

stdint.h文件如下：

/* Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.This file is part of the GNU C Library.The GNU C Library is free software; you can redistribute it and/ormodify it under the terms of the GNU Lesser General PublicLicense as published by the Free Software Foundation; eitherversion 2.1 of the License, or (at your option) any later version.The GNU C Library is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNULesser General Public License for more details.You should have received a copy of the GNU Lesser General PublicLicense along with the GNU C Library; if not, write to the FreeSoftware Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307 USA. *//** ISO C99: 7.18 Integer types <stdint.h>*/#ifndef _STDINT_H#define _STDINT_H   1#include <features.h>#include <bits/wchar.h>#include <bits/wordsize.h>/* Exact integral types. *//* Signed. *//* There is some amount of overlap with <sys/types.h> as known by inet code */#ifndef __int8_t_defined# define __int8_t_definedtypedef signed char     int8_t;typedef short int       int16_t;typedef int         int32_t;# if __WORDSIZE == 64typedef long int        int64_t;# else__extension__typedef long long int       int64_t;# endif#endif/* Unsigned. */typedef unsigned char       uint8_t;typedef unsigned short int uint16_t;#ifndef __uint32_t_definedtypedef unsigned int        uint32_t;# define __uint32_t_defined#endif#if __WORDSIZE == 64typedef unsigned long int   uint64_t;#else__extension__typedef unsigned long long int uint64_t;#endif/* Small types. *//* Signed. */typedef signed char     int_least8_t;typedef short int       int_least16_t;typedef int         int_least32_t;#if __WORDSIZE == 64typedef long int        int_least64_t;#else__extension__typedef long long int       int_least64_t;#endif/* Unsigned. */typedef unsigned char       uint_least8_t;typedef unsigned short int uint_least16_t;typedef unsigned int        uint_least32_t;#if __WORDSIZE == 64typedef unsigned long int   uint_least64_t;#else__extension__typedef unsigned long long int uint_least64_t;#endif/* Fast types. *//* Signed. */typedef signed char     int_fast8_t;#if __WORDSIZE == 64typedef long int        int_fast16_t;typedef long int        int_fast32_t;typedef long int        int_fast64_t;#elsetypedef int         int_fast16_t;typedef int         int_fast32_t;__extension__typedef long long int       int_fast64_t;#endif/* Unsigned. */typedef unsigned char       uint_fast8_t;#if __WORDSIZE == 64typedef unsigned long int   uint_fast16_t;typedef unsigned long int   uint_fast32_t;typedef unsigned long int   uint_fast64_t;#elsetypedef unsigned int        uint_fast16_t;typedef unsigned int        uint_fast32_t;__extension__typedef unsigned long long int uint_fast64_t;#endif/* Types for `void *' pointers. */#if __WORDSIZE == 64# ifndef __intptr_t_definedtypedef long int        intptr_t;# define __intptr_t_defined# endiftypedef unsigned long int   uintptr_t;#else# ifndef __intptr_t_definedtypedef int         intptr_t;# define __intptr_t_defined# endiftypedef unsigned int        uintptr_t;#endif/* Largest integral types. */#if __WORDSIZE == 64typedef long int        intmax_t;typedef unsigned long int   uintmax_t;#else__extension__typedef long long int       intmax_t;__extension__typedef unsigned long long int uintmax_t;#endif/* The ISO C99 standard specifies that in C++ implementations thesemacros should only be defined if explicitly requested. */#if !defined __cplusplus || defined __STDC_LIMIT_MACROS# if __WORDSIZE == 64# define __INT64_C(c) c ## L# define __UINT64_C(c) c ## UL# else# define __INT64_C(c) c ## LL# define __UINT64_C(c) c ## ULL# endif/* Limits of integral types. *//* Minimum of signed integral types. */# define INT8_MIN       (-128)# define INT16_MIN      (-32767-1)# define INT32_MIN      (-2147483647-1)# define INT64_MIN      (-__INT64_C(9223372036854775807)-1)/* Maximum of signed integral types. */# define INT8_MAX       (127)# define INT16_MAX      (32767)# define INT32_MAX      (2147483647)# define INT64_MAX      (__INT64_C(9223372036854775807))/* Maximum of unsigned integral types. */# define UINT8_MAX      (255)# define UINT16_MAX     (65535)# define UINT32_MAX     (4294967295U)# define UINT64_MAX     (__UINT64_C(18446744073709551615))/* Minimum of signed integral types having a minimum size. */# define INT_LEAST8_MIN     (-128)# define INT_LEAST16_MIN    (-32767-1)# define INT_LEAST32_MIN    (-2147483647-1)# define INT_LEAST64_MIN    (-__INT64_C(9223372036854775807)-1)/* Maximum of signed integral types having a minimum size. */# define INT_LEAST8_MAX     (127)# define INT_LEAST16_MAX    (32767)# define INT_LEAST32_MAX    (2147483647)# define INT_LEAST64_MAX    (__INT64_C(9223372036854775807))/* Maximum of unsigned integral types having a minimum size. */# define UINT_LEAST8_MAX    (255)# define UINT_LEAST16_MAX   (65535)# define UINT_LEAST32_MAX   (4294967295U)# define UINT_LEAST64_MAX   (__UINT64_C(18446744073709551615))/* Minimum of fast signed integral types having a minimum size. */# define INT_FAST8_MIN      (-128)# if __WORDSIZE == 64# define INT_FAST16_MIN    (-9223372036854775807L-1)# define INT_FAST32_MIN    (-9223372036854775807L-1)# else# define INT_FAST16_MIN    (-2147483647-1)# define INT_FAST32_MIN    (-2147483647-1)# endif# define INT_FAST64_MIN     (-__INT64_C(9223372036854775807)-1)/* Maximum of fast signed integral types having a minimum size. */# define INT_FAST8_MAX      (127)# if __WORDSIZE == 64# define INT_FAST16_MAX    (9223372036854775807L)# define INT_FAST32_MAX    (9223372036854775807L)# else# define INT_FAST16_MAX    (2147483647)# define INT_FAST32_MAX    (2147483647)# endif# define INT_FAST64_MAX     (__INT64_C(9223372036854775807))/* Maximum of fast unsigned integral types having a minimum size. */# define UINT_FAST8_MAX     (255)# if __WORDSIZE == 64# define UINT_FAST16_MAX   (18446744073709551615UL)# define UINT_FAST32_MAX   (18446744073709551615UL)# else# define UINT_FAST16_MAX   (4294967295U)# define UINT_FAST32_MAX   (4294967295U)# endif# define UINT_FAST64_MAX    (__UINT64_C(18446744073709551615))/* Values to test for integral types holding `void *' pointer. */# if __WORDSIZE == 64# define INTPTR_MIN        (-9223372036854775807L-1)# define INTPTR_MAX        (9223372036854775807L)# define UINTPTR_MAX       (18446744073709551615UL)# else# define INTPTR_MIN        (-2147483647-1)# define INTPTR_MAX        (2147483647)# define UINTPTR_MAX       (4294967295U)# endif/* Minimum for largest signed integral type. */# define INTMAX_MIN     (-__INT64_C(9223372036854775807)-1)/* Maximum for largest signed integral type. */# define INTMAX_MAX     (__INT64_C(9223372036854775807))/* Maximum for largest unsigned integral type. */# define UINTMAX_MAX        (__UINT64_C(18446744073709551615))/* Limits of other integer types. *//* Limits of `ptrdiff_t' type. */# if __WORDSIZE == 64# define PTRDIFF_MIN       (-9223372036854775807L-1)# define PTRDIFF_MAX       (9223372036854775807L)# else# define PTRDIFF_MIN       (-2147483647-1)# define PTRDIFF_MAX       (2147483647)# endif/* Limits of `sig_atomic_t'. */# define SIG_ATOMIC_MIN     (-2147483647-1)# define SIG_ATOMIC_MAX     (2147483647)/* Limit of `size_t' type. */# if __WORDSIZE == 64# define SIZE_MAX      (18446744073709551615UL)# else# define SIZE_MAX      (4294967295U)# endif/* Limits of `wchar_t'. */# ifndef WCHAR_MIN/* These constants might also be defined in <wchar.h>. */# define WCHAR_MIN     __WCHAR_MIN# define WCHAR_MAX     __WCHAR_MAX# endif/* Limits of `wint_t'. */# define WINT_MIN       (0u)# define WINT_MAX       (4294967295u)#endif /* C++ && limit macros *//* The ISO C99 standard specifies that in C++ implementations theseshould only be defined if explicitly requested. */#if !defined __cplusplus || defined __STDC_CONSTANT_MACROS/* Signed. */# define INT8_C(c) c# define INT16_C(c) c# define INT32_C(c) c# if __WORDSIZE == 64# define INT64_C(c)    c ## L# else# define INT64_C(c)    c ## LL# endif/* Unsigned. */# define UINT8_C(c) c ## U# define UINT16_C(c)    c ## U# define UINT32_C(c)    c ## U# if __WORDSIZE == 64# define UINT64_C(c)   c ## UL# else# define UINT64_C(c)   c ## ULL# endif/* Maximal type. */# if __WORDSIZE == 64# define INTMAX_C(c)   c ## L# define UINTMAX_C(c) c ## UL# else# define INTMAX_C(c)   c ## LL# define UINTMAX_C(c) c ## ULL# endif#endif /* C++ && constant macros */#endif /* stdint.h */