C中二分查找法怎么写呀

Question

二分查找法怎么写呀,在数组中找到指定的元素？？？ 救救孩子吧，刚学c语言

Answer 1

#include<iostream>
#include<assert.h>
using namespace std;
int Search(int ar[], int n, int key)
{
    int low = 0;//低位值
    int high = n-1;//高位值是元素个数-1
    int mid;
    while(low <= high)
    {
        mid = (low+high)/2;
        if(key < ar[mid])
        {
            high = mid-1;//二分
        }
        else if(key > ar[mid])
        {
            low = mid+1;//二分
        }
        else
            return mid;//找到值
    }
    return -1;//查找数据不存在
}
void main()
{
    int ar[10] = {12,23,34,45,56,67,78,89,90,100};//这种算法只能在数组有序的情况使用，如果无序，先进行排序
    int n = sizeof(ar)/sizeof(int);
    int key;
    cout<<"请输入要查找的key值:>";
    cin>>key;
    cout<<"pos :> "<<Search(ar,n,key)<<endl;
}