sizet和ssizet的含义和区别.doc

size_t和ssize_t的含义和区别 stddef.h C 语言头文件。 作用：定义/声明了一些经常使用的常数，类型和变量 VC 中stddef.h 的内容： /*** *stddef.h - definitions/declarations for common constants, types, variables * * Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved. * *Purpose: * This file contains definitions and declarations for some commonly * used constants, types, and variables. * [ANSI] * * [Public] * ****/ #if _MSC_VER 1000 #pragma once #endif #ifndef _INC_STDDEF #define _INC_STDDEF #if !defined(_WIN32) !defined(_MAC) #error ERROR: Only Mac or Win32 targets supported! #endif #ifdef __cplusplus extern C { #endif /* Define _CRTIMP */ #ifndef _CRTIMP #ifdef _DLL #define _CRTIMP __declspec(dllimport) #else /* ndef _DLL */ #define _CRTIMP #endif /* _DLL */ #endif /* _CRTIMP */ /* Define __cdecl for non-Microsoft compilers */ #if ( !defined(_MSC_VER) !defined(__cdecl) ) #define __cdecl #endif /* Define _CRTAPI1 (for compatibility with the NT SDK) */ #ifndef _CRTAPI1 #if _MSC_VER = 800 _M_IX86 = 300 #define _CRTAPI1 __cdecl #else #define _CRTAPI1 #endif #endif /* Define NULL pointer value and the offset() macro */ #ifndef NULL #ifdef __cplusplus #define NULL 0 #else #define NULL ((void *)0) #endif #endif #define offsetof(s,m) (size_t)(((s *)0)-m) /* Declare reference to errno */ #if (defined(_MT) || defined(_DLL)) !defined(_MAC) _CRTIMP extern int * __cdecl _errno(void); #define errno (*_errno()) #else /* ndef _MT ndef _DLL */ _CRTIMP extern int errno; #endif /* _MT || _DLL */ /* define the implementation dependent size types */ //定义依赖于实现规模类型 #ifndef _PTRDIFF_T_DEFINED typedef int ptrdiff_t; #define _PTRDIFF_T_DEFINED #endif #ifndef _SIZE_T_DEFINED typedef unsigned int size_t; #define _SIZE_T_DEFINED #endif #ifndef _WCHAR_T_DEFINED typedef unsigned short wchar_t; #define _WCHAR_T_DEFINED #endif #ifdef _MT _CRTIMP extern unsigned long __cdecl __threadid(void); #define _threadid (__threadid()) _CRTIMP extern unsigned long __cdecl __threadhandle(void); #endif #ifdef __cplusplus } #endif #endif