二分查找

#include <iostream>
using namespace std;
#define len 10
int source[]={6,12,28,37,54,65,69,83,90,92};
int search(int s[],int n,int key)
{
    int left,right,mid;
    left=0;
    right=n-1;
    while(left<=right)        //查找范围含含至少一个元素 
    {
        mid=(left+right)/2;   
        if(s[mid]==key)     
            return mid;
        else if(s[mid]>key)
            right=mid-1;
        else 
            left=mid+1;
    }
    return -1;
}

int main()
{
    int key,i,pos;     
    cout<<"原数据表:"<<endl; 
    for(i=0;i<len;i++)
       cout<<source[i]<<" ";
    cout<<endl;
    cout<<"请输入关键字:";
    cin>>key;  
    pos=search(source,len,key);
    if(pos>=0)
        cout<<"查找成功，该关键字位于数组的第"<<pos+1<<"个位置"<<endl;
    else
        cout<<"查找失败!\n"<<endl;;
    return 0;
}