C语言库函数的原型,有用的拿去

				/***
				*stddef.h - definitions/declarations for common constants, types, variables
				*
				*       Copyright (c) Microsoft Corporation. All rights reserved.
				*
				*Purpose:
				*       This file contains definitions and declarations for some commonly
				*       used constants, types, and variables.
				*       [ANSI]
				*
				*       [Public]
				*
				****/
				
				#pragma once
				
				#ifndef _INC_STDDEF
				#define _INC_STDDEF
				
				#include 
				
				#ifdef __cplusplus
				extern "C" {
				#endif  /* __cplusplus */
				
				/* Define NULL pointer value */
				#ifndef NULL
				#ifdef __cplusplus
				#define NULL    0
				#else  /* __cplusplus */
				#define NULL    ((void *)0)
				#endif  /* __cplusplus */
				#endif  /* NULL */
				
				
				#ifdef __cplusplus
				#ifdef _NATIVE_NULLPTR_SUPPORTED
				namespace std { typedef decltype(__nullptr) nullptr_t; }
				using ::std::nullptr_t;
				#endif  /* _NATIVE_NULLPTR_SUPPORTED */
				#endif  /* __cplusplus */
				
				
				/* Declare reference to errno */
				#ifndef _CRT_ERRNO_DEFINED
				#define _CRT_ERRNO_DEFINED
				_CRTIMP extern int * __cdecl _errno(void);
				#define errno   (*_errno())
				
				errno_t __cdecl _set_errno(_In_ int _Value);
				errno_t __cdecl _get_errno(_Out_ int * _Value);
				#endif  /* _CRT_ERRNO_DEFINED */
				
				/* Define offsetof macro */
				#ifdef __cplusplus
				
				#ifdef _WIN64
				#define offsetof(s,m)   (size_t)( (ptrdiff_t)&reinterpret_cast((((s *)0)->m)) )
				#else  /* _WIN64 */
				#define offsetof(s,m)   (size_t)&reinterpret_cast((((s *)0)->m))
				#endif  /* _WIN64 */
				
				#else  /* __cplusplus */
				
				#ifdef _WIN64
				#define offsetof(s,m)   (size_t)( (ptrdiff_t)&(((s *)0)->m) )
				#else  /* _WIN64 */
				#define offsetof(s,m)   (size_t)&(((s *)0)->m)
				#endif  /* _WIN64 */
				
				#endif  /* __cplusplus */
				
				_CRTIMP extern unsigned long  __cdecl __threadid(void);
				#define _threadid       (__threadid())
				_CRTIMP extern uintptr_t __cdecl __threadhandle(void);
				
				#ifdef __cplusplus
				}
				#endif  /* __cplusplus */
				
				#endif  /* _INC_STDDEF */