c++ - 通过提供指针数组作为参数对数组进行排序

Question

我写了这段代码，但它只是给我一个地址:

#include<iostream>
using namespace std;

void swap(int* a,int* b) 
{
    int temp=*a;
    *a=*b;
    *b=temp;
}

void sort(int* p[],int n) 
{
    for(int i=0; i<n;i++)
    {
        if(*p[i]>*p[i+1])
        swap(p[i],p[i+1]);
    }
}

int main()
{
    int arr[]={8,6,5,4,3,7,1};
    int* p[7];

    for(int i=0;i<7;i++)
    {
        p[i]=&arr[i];
    }

    sort(p,7);

    /*i tried to change arr[1] to p[1] or *p[1] but same output*/
    cout<<arr[1]<<arr[2];
    return 0;
}

我觉得我在某个地方缺乏概念。完整的问题是这样的:

Write the following function that indirectly sorts the floats pointed to by the first n pointers in the array p by rearranging the pointers: void sort(float* p[],int n)

请帮忙。

Answer 1

这是一个更好的方法来做你想做的事情，有很多方法可以做得更好，但它看起来像你的 c++ 新手，所以我尽量让它尽可能简单。

#include "stdafx.h"
#include<iostream>
using namespace std;

//not needed, std::swap does the same job!
void swap(int *a, int *b)
{
    std::swap(a, b);
}

//using a pointer to the array is better!
void sort(int arr[], int n)
{
    //two loops are needed to sort the entire array!
    for (int x(0); x < n - 1; x++)
    {
        //optimize the loop by removing already sorted items from loop
        int sorted = n - x;
        for (int y(0); y < sorted - 1; ++y)
            if (arr[y] > arr[y + 1])
                std::swap(arr[y], arr[y + 1]);
    }
}


int main()
{
    //vector or std::array better option!
    int arr[] { 8,6,5,4,3,7,1 };

    //provide the array to sort(), no need to make stuff harder
    sort(arr, 7);

    //Show you that the sort worked!
    for (int ccc = 0; ccc < 7; ccc++)
        std::cout << arr[ccc] << ' ';

    std::cout << '\n';

    cout << "Index 5: " << arr[5] << "\nIndex 6: " << arr[6] << "\n";

    return 0;
}

这里有一个很好的数组排序教程:http://www.learncpp.com/cpp-tutorial/64-sorting-an-array-using-selection-sort/