自訂一個strcmp (c++)

#include <iostream>
using namespace std;
int strcmp2(const char *dest, const char *ori);
int main(void){
        cout<<strcmp2("aello","a")<<endl;
        return 0;
}
int strcmp2(const char *dest, const char *ori){
        assert(ori !=NULL && dest!=NULL);
        int tmp =0;
        while(!(tmp = *(unsigned char*)dest - *(unsigned char*)ori)&&*ori){
                ++dest;
                ++ori;
        }
        if(tmp <0){
                tmp= -1;
        }else if(tmp >0){
                tmp=1;
        }
        return tmp;
}