指定字符串长度的复制

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
void *memcpy(void *dest,void const *scr,size_t length)
{

char *ret=(char*)dest;
char *src=(char*)scr;
int flag=0;
int n=length;

while(length)
{
if(ret==src+1)
{
if(flag==0)
{
while(length)
{
src[length]=src[length-1];
length--;
}
length=n;
flag=1;
}
while(length--)
{
*ret++=*(++src);
}
*ret='\0';
return dest;
}
else
{
*ret++=*src++;
}
length--;
}
*ret='\0';
return dest;
}
void main()
{
char scr[]="abcdefgh";
char dest[10]={0};
//	char *ret=(char*)memcpy(dest,scr,4);
char *ret=(char*)memcpy(scr+1,scr,4);
printf("%s\n",ret);
}

<span style="font-family: Arial, Helvetica, sans-serif;">总结：实现char *ret=(char*)memcpy(dest,scr,4)时很简单,但将自身的字符串复制到自身的下一个时就需要好好想一想，即实现char*=(char*)memcpy(scr+1,scr,4)</span>