代码

int binary_search(const unsigned *a,const int n, unsigned x)
{
	register unsigned l = 0, r = 99999999;
	for(;;) {
		register const unsigned mid = l + r >> 1;
		if ( a[mid] == x ) return mid;
		else if (a[mid] > x ) r = mid - 1;
		else l = mid + 1;
	}
}

评测结果