代码

int binary_search(const unsigned *a, int n, unsigned value)
{register const unsigned *it,*beg;register int step;
beg=a;
    while (n > 0) {
        it = a; 
        step = n >>1; 
        it += step;
        if (*it < value) {
            a = ++it; 
            n -= step + 1; 
        }
        else if(*it==value) {a=it;break;}
        else 
            n = step;
    }
    return a-beg;
}

评测结果