一般来说，一个C的工程中一定要做一些这方面的工作，因为你会涉及到跨平台，不同的平台会有不同的字长，所以利用预编译和typedef可以让你最有效的维护你的代码。为了用户的方便，C99标准的C语言硬件为我们定义了这些类型，我们放心使用就可以了。
按照posix标准，一般整形对应的*_t类型为：
1字节 uint8_t
2字节 uint16_t
4字节 uint32_t
8字节 uint64_t
附：C99标准中inttypes.h的内容
00001 /*
00002 inttypes.h
00003
00004 Contributors:
00005 Createdby Marek Michalkiewicz <marekm@linux.org.pl>
00006
00007 THISSOFTWARE IS NOT COPYRIGHTED
00008
00009 Thissource code is offered for use in the public domain. You may
00010 use,modify or distribute it freely.
00011
00012 Thiscode is distributed in the hope that it will be useful, but
00013 WITHOUTANY WARRANTY. ALLWARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
00014 DISCLAIMED. This includes but is not limited towarranties of
00015 MERCHANTABILITYor FITNESS FOR A PARTICULAR PURPOSE.
00016 */
00017
00018 #ifndef __INTTYPES_H_
00019 #define __INTTYPES_H_
00020
00021 /* Use [u]intN_t if you need exactly N bits.
00022 XXX- doesn't handle the -mint8 option. */
00023
00024 typedefsigned char int8_t;
00025 typedefunsigned char uint8_t;
00026
00027 typedefint int16_t;
00028 typedefunsigned int uint16_t;
00029
00030 typedeflong int32_t;
00031 typedefunsigned long uint32_t;
00032
00033 typedeflong long int64_t;
00034 typedefunsigned long long uint64_t;
00035
00036 typedefint16_t intptr_t;
00037 typedefuint16_t uintptr_t;
00038
00039 #endif