[英]Struggling to sort an array of structs using an array of pointers. C++
所以我試圖通過使用指針數組來對結構數組進行排序。 我正在嘗試根據Test
結構的int score
成員對結構進行排序。 我遇到了很多錯誤,我認為它們都與我做錯的特定事情有關。 (或者我只是顯然對這一切的工作原理沒有絲毫的了解。)
錯誤如下: 錯誤列表的屏幕截圖
這是代碼:
#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
struct Test;
void selectionSort(int num, struct Test* sortArray[]);
int main()
{
const int NO_ERRRORS = 0;
int num, scoreIn;
string nameIn;
cout << "Please provide the number of test scores you would " << endl
<< "like to average and sort." << endl << endl
<< "Please limit your request to 5-20 tests: ";
cin >> num;
while ((num < 5) || (num > 20))
{
cout << "Invalid entry. Please enter an integer between 5-20: ";
cin >> num;
}
cout << endl;
Test* tests = new Test[num];
Test** sortArray = new Test*[num];
cout << "Please enter first names only with no spaces." << endl << endl;
for (int index = 0; index < num; index++)
{
cout << "Please enter the name of student " << (index + 1) << ": ";
cin >> nameIn;
cout << "Enter the test score: ";
cin >> scoreIn;
while (scoreIn < 0)
{
cout << "Invalid entry. Please enter a positive integer: ";
cin >> scoreIn;
}
cout << endl;
((*(tests + index)) = { nameIn, scoreIn }); //IntelliSense: no operator "=" matches operands. Operand types are Test = {..}
sortArray[index] = &tests[index];
}
selectionSort(num, sortArray);
for (int count = 0; count < num; count++)
cout << (sortArray[count]->score) << " ";
cout << endl;
for (int count = 0; count < num; count++)
cout << (sortArray[count]->name) << " ";
cout << endl;
delete[] tests;
cin.ignore(cin.rdbuf()->in_avail(), '\n');
cout << endl << "Press only the 'Enter' key to exit program: ";
cin.get();
return NO_ERRRORS;
}
void selectionSort(int num, struct Test* sortArray[])
{
int minIndex;
Test *minElem;
for (int scan = 0; scan < (num - 1); scan++)
{
minIndex = scan;
minElem = sortArray[scan];
for (int index = scan + 1; index < num; index++)
{
if ((*(sortArray[index])) < (*minElem)) //IntelliSense: no operator "<" matches operands. Operand types are Test < Test
{
minElem = sortArray[index];
minIndex = index;
}
}
sortArray[minIndex] = sortArray[scan];
sortArray[scan] = minElem;
}
}
struct Test
{
int num = num;
Test()
{
name = "";
score = 0;
}
string name;
int score;
};
顯然,我並沒有要求任何人為我做我的工作。 但是有人可以……從概念上向我指出正確的方向嗎? 也許指出我首先出錯的地方並導致了一系列錯誤?
任何幫助,非常感謝。
編輯:我搞砸了,忘了提到我正在工作的約束。1.必須使用選擇排序。
通過這些對象的成員對對象容器進行排序比這容易得多。
#include <vector>
#include <algorithm>
#include <string>
struct Test
{
Test()
: score(0)
, num(0)
{}
std::string name;
int score;
int num;
};
int main()
{
const unsigned int num = 5; // user input in your case
std::vector<Test> v(num);
//!! Assign values to items in `v`
std::sort(
v.begin(),
v.end(),
[](const Test& lhs, const Test& rhs) {
return lhs.num < rhs.num;
}
);
}
實際上只有一個整數的struct並不能使它成為整數,它仍然是一個struct。 為了比較對象(實際上是一個結構產生的對象),您需要重載比較運算符,在這種情況下,請重載>運算符。
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