memcpy, strncpy, strcpy

最新推荐文章于 2025-04-08 14:13:16 发布

转载最新推荐文章于 2025-04-08 14:13:16 发布 · 660 阅读

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#string #function #access #io

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本文介绍了内存复制函数memcpy以及字符串复制函数strncpy和strcpy的实现原理。这些函数用于在C语言中高效地处理内存和字符串数据，是程序员必须掌握的基础技能。

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/** * memcpy - Copy one area of memory to another * @dest: Where to copy to * @src: Where to copy from * @count: The size of the area. * * You should not use this function to access IO space, use memcpy_toio() * or memcpy_fromio() instead. */ void * memcpy(void * dest,const void *src,size_t count) { char *tmp = (char *) dest, *s = (char *) src; while (count--) *tmp++ = *s++; return dest; } /** * strncpy - Copy a length-limited, %NUL-terminated string * @dest: Where to copy the string to * @src: Where to copy the string from * @count: The maximum number of bytes to copy * * Note that unlike userspace strncpy, this does not %NUL-pad the buffer. * However, the result is not %NUL-terminated if the source exceeds * @count bytes. */ char * strncpy(char * dest,const char *src,size_t count) { char *tmp = dest; while (count-- && (*dest++ = *src++) != '/0') /* nothing */; return tmp; } /** * strcpy - Copy a %NUL terminated string * @dest: Where to copy the string to * @src: Where to copy the string from */ char * strcpy(char * dest,const char *src) { char *tmp = dest; while ((*dest++ = *src++) != '/0') /* nothing */; return tmp; }