二分搜索模板

#include<stdio.h>

int binary(int a[],int key,int len)
{
    int low,high,mid;
    low=0,high=len-1;
    while(low<=high)
    {
        mid=(low+high)/2;
        if(key==a[mid]) return mid;
        else if(key>a[mid])
            low=mid+1;
        else
            high=mid-1;
    }
    return -1;
}

int main()
{
    int a[11]={1,2,4,5,10,11,12,13,14,15};
    int key;

    while(scanf("%d",&key)!=EOF && key)
    {
    int index= binary(a,key,10);
    printf("%d\n",index);
    }
    return 0;
}