C语言里的几个拷贝函数memcpy、memset、strcpy、strncpy

#include<string.h>

1. src和dest所指内存区域不能重叠，函数返回指向dest的指针。memcpy用来做内存拷贝，你可以拿它拷贝任何数据类型的对象，可以指定拷贝的数据长度

void *memcpy(>const void *src,size_t count );

2. 把buffer所指内存区域的前count个字节设置成字符c.说明：返回指向buffer的指针。

void *memset ( void  *dest,  int         c         ,size_tcount );

3. src和dest所指内存区域不可以重叠且dest必须有足够的空间来容纳src的字符串

​

char        *strcpy      ( char                  *strDestination,const char                 *strSource);
wchar_t    *wcscpy   ( wchar_t            *strDestination,const wchar_t            *strSource);
unsigned char  *_mbscpy( unsigned char  *strDestination, constunsigned char  *strSource );

4. 把src所指示的以'\0'结尾的字符串的前n个字节复制到dest所指的数组中。复制时连同字符串的'\0'一起被复制。

char           *strncpy      (char                    *strDest,const char                  *strSource,size_t count );
       wchar_t     *wcsncpy   ( wchar_t              *strDest,const wchar_t            *strSource,size_t count );
unsigned char  *_mbsncpy (unsigned char  *strDest,const unsigned char  *strSource,size_t count );

 STRING.H 

#ifdef  _M_MRX000
 _CRTIMP void *  __cdecl memcpy(void *, const void *, size_t);
 _CRTIMP int        __cdecl memcmp(const void *, const void *, size_t);
 _CRTIMP void *  __cdecl memset(void *, int, size_t);
 _CRTIMP char *  __cdecl _strset(char *, int);
 _CRTIMP char *  __cdecl strcpy(char *, const char *);
 _CRTIMP char *  __cdecl strcat(char *, const char *);
 _CRTIMP int        __cdecl strcmp(const char *, const char *);
 _CRTIMP size_t  __cdecl strlen(const char *);
 #else
         void *  __cdecl memcpy(void *, const void *, size_t);
         int       __cdecl memcmp(const void *, const void *, size_t);
         void *  __cdecl memset(void *, int, size_t);
         char *  __cdecl _strset(char *, int);
         char *  __cdecl strcpy(char *, const char *);
         char *  __cdecl strcat(char *, const char *);
         int        __cdecl strcmp(const char *, const char *);
         size_t  __cdecl strlen(const char *);
 #endif