校園招聘面試題之重寫系統函數

1.已知memcpy的函數爲： void* memcpy(void *dest , const void* src , size_t count)其中dest是目的指針，src是源指針。不調用c++/c的memcpy庫函數，請編寫memcpy。

void* memcpy(void *dst, const void *src, size_t count)      
{      
    //安全檢查  
    assert( (dst != NULL) && (src != NULL) );      
  
    unsigned char *pdst = (unsigned char *)dst;      
    const unsigned char *psrc = (const unsigned char *)src;      
  
    //防止內存重複  
    assert(!(psrc<=pdst && pdst<psrc+count));      
    assert(!(pdst<=psrc && psrc<pdst+count));      
  
    while(count--)      
    {      
        *pdst = *psrc;      
        pdst++;      
        psrc++;      
    }      
    return dst;      
}