#include <iostream>
using namespace std;


//快排
void quickSort(double *q ,int n)   //一个double型数组还有一个代表这个数组的位数。 
{

    double *left,*right;
    left = &q[0];
    right = &q[n-1];
    double middle = q[0];
//    cout<<"left指向数组第一位，值为"<<*left<<endl;
//    cout<<"right指向数组最右一位，值为"<<*right<<endl;
    while(left != right)
    {
        if (*right < middle)
        {
            *left = *right;
            while (*left < middle)
            {
                left++;
                if (left == right)
                {
                    break;
                }
            }
            *right = *left;
        } else {
            right--;
        }

    }
    //左右指针指向一致时把middle给这个位置
    *left = middle;

    //接下来取得*left和*right指向数组的位数
    int count = 0;   //count1表示有count1个数在middle左边，最小为0
    for(;q[count]<middle;count++) { }
    //
    //处理middle的左边
    if (count>1)
    {
        double *qq = new double[count];
        qq = q;
        quickSort(qq,count);
    }
    
    //处理middle的右边
    int count2 = n-count-1; //count2表示有count2个数在middle右边，最小为0
    if (count2 > 1)
    {
        double *ww = new double[count2];
        ww = left+1;
        quickSort(ww,count2);
    }
    
}


//折半查找
void binarySearch(double *p ,int length,double g) {
    bool b = false;
    int left = 1,right = length;
    int middle = (left + right) / 2;
    if (g == p[middle-1])
    {
        cout<<"该数字是第"<<middle<<"位"<<endl;
    } else {
        while (g != p[middle-1])
        {
            if (left == right)
            {
                cout<<"该数字不在数组中"<<endl;
                b = true;
                break;
            }
            if (g>p[middle-1])   //因为数组从零开始所以减一
            {
                left = middle + 1;
            } else {
                right = middle - 1;
            }
            middle = (left + right) / 2;
        }
        if (b == false)
        {
            cout<<"该数字是第"<<middle<<"位"<<endl;
        }
        
        
    }
}



int main() {
    cout<<"请输入数组长度";
    int n;
    cin>>n;
    double *p = new double[n];
    for (int i = 0;i<n;i++)
    {
        cin>>p[i];
    }
    quickSort(p,n);
    for (int xxx = 0;xxx<n;xxx++)
    {
        cout<<p[xxx]<<"    ";
    }


    cout<<endl<<endl;
    //设(left+right)/2是中间位置
    double g;
    cout<<"输入要查的数字"<<endl;
    cin>>g;
    binarySearch(p,n,g);
    return 0;
}

结果如图