二分查找 简易版

二分查找 简易版

参考 K&R C

#include <stdio.h>
//binsearch函数: 在v[0..n-1]中查找x,其中v[i]<=v[i+1]
//若找到返回下标(0-base)，若找不到返回-1;
int binsearch(int v[], int x, int low,int high){
    int mid;
    while(low<=high){
        mid=(low+high)/2;
        if(v[mid]==x){
            return mid;
        }
        else if(v[mid]>x){
            high=mid-1;
        }
        else if(v[mid]<x){
            low=mid+1;
        }
    }
    return -1;
}
int main(){
    int v[]={1,2,3,4,5,6,7,8};
    int x;
    while(1){
        scanf("%d",&x);
        if(x==100)
            break;
        else
            printf("the index of x is %d
",binsearch(v,x,0,7));
    }
    printf("break while
");
    getchar();
    return 0;
}

运行结果