代码

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

评测结果