strcpy、memcpy c语言实现

以下代码没有考虑重叠的情况

//strcpy
char *__strcpy(char *dest, const char *src)
{
   if(dest == NULL || src == NULL)
        return NULL;
    char *strdest = dest;
    while((*dest++ = *src++) != '\0')
    return strdest;
}


//memcpy
char *__memcpy(void *memTo, const void *memFrom, size_t size)
    {
        char *tmpTo = (char*)memTo;
        const char *tmpFrom = (const char *)memFrom;
    if(memTo == NULL || memFrom == NULL)
        return NULL;
    while(size-- > 0)
        {
            *tmpTo++ = *tmpFrom++;
        }
    return memTo;
    }