stdint.h 文件 int8_t uint8_t int16_t uint16_t （一）

按照posix标准，一般整型对应的*_t类型为：
1字节     uint8_t
2字节     uint16_t
4字节     uint32_t
8字节     uint64_t

/* 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/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 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 of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 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_defined
typedef signed char     int8_t;
typedef short int       int16_t;
typedef int         int32_t;
# if __WORDSIZE == 64
typedef 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_defined
typedef unsigned int        uint32_t;
# define __uint32_t_defined
#endif
#if __WORDSIZE == 64
typedef 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 == 64
typedef 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 == 64
typedef 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 == 64
typedef long int        int_fast16_t;
typedef long int        int_fast32_t;
typedef long int        int_fast64_t;
#else
typedef 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 == 64
typedef unsigned long int   uint_fast16_t;
typedef unsigned long int   uint_fast32_t;
typedef unsigned long int   uint_fast64_t;
#else
typedef 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_defined
typedef long int        intptr_t;
# define __intptr_t_defined
# endif
typedef unsigned long int   uintptr_t;
#else
# ifndef __intptr_t_defined
typedef int         intptr_t;
# define __intptr_t_defined
# endif
typedef unsigned int        uintptr_t;
#endif


/* Largest integral types. */
#if __WORDSIZE == 64
typedef 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