如何从向量中打印某些元素?

问题描述

我正在尝试打印程序中需要的所有内容.它的作用是从文本文件中提取一长串列表，并根据首选和GPA对其进行排序，然后将其放入向量中.我设法按首选和GPA进行排序，但是如何删除不需要的输出呢?

I am trying to print out whatever is necessary from my program. What it does is it takes a long list from a text file and sort it based on first choice and GPA and put it into a vector. I manage to sort by First choice and GPA however how can I remove whatever output that isn't necessary?

这是我的Txt文件的示例(每行的顺序是第一选择，第二选择，第三选择，GPA，名称):

This is an example of my Txt File (The sequence of each line is 1st choice, 2nd choice, 3rd choice, GPA, Name):

CC,DR,TP,3.8,AlexKong
SN,SM,TP,4,MarcusTan
DR,TP,SC,3.6,AstaGoodwin
SC,TP,DR,2.8,MalcumYeo
SN,SM,TP,3.7,DavidLim
SN,SM,TP,3.2,SebastianHo
SC,TP,DR,4,PranjitSingh
DR,TP,SC,3.7,JacobMa
and so on...

这是我的输出(这是一个很长的向量):

This is my output now (it is a long vector):

TP,DR,SC,4,SitiZakariah
TP,DR,SC,3.9,MuttuSami
TP,DR,SC,3.5,SabrinaEster
TP,DR,SC,3,KarimIlham
TP,DR,SC,3,AndryHritik
SN,SM,TP,4,MarcusTan
SN,SM,TP,3.8,MarcusOng
SN,SM,TP,3.7,DavidLim
SN,SM,TP,3.4,MollyLau
SN,SM,TP,3.2,SebastianHo
SN,SM,TP,3.2,NurAfiqah
SN,SM,TP,2.4,TanXiWei
SC,TP,DR,4,SallyYeo
SC,TP,DR,4,PranjitSingh
SC,TP,DR,3.6,RanjitSing
SC,TP,DR,2.8,MalcumYeo
SC,TP,DR,2.8,AbdulHalim
SC,TP,DR,2.7,AlifAziz
DR,TP,SC,3.9,SitiAliyah
DR,TP,SC,3.9,LindaChan
DR,TP,SC,3.8,SohLeeHoon
DR,TP,SC,3.7,PrithikaSari
DR,TP,SC,3.7,NurAzizah
DR,TP,SC,3.7,JacobMa
DR,TP,SC,3.6,AstaGoodwin
CC,DR,TP,3.9,MuruArun
CC,DR,TP,3.8,AlexKong
CC,DR,TP,3.7,DamianKoh
CC,DR,TP,3.3,MattWiliiams
CC,DR,TP,3.3,IrfanMuhaimin

这是我需要的输出(基本上是将CC作为第一选择的学生，而不显示3个选项):

And this is the output that I need (Basically students with CC as their 1st choice without displaying the 3 options):

3.9,MuruArun
3.8,AlexKong
3.7,DamianKoh
3.3,MattWiliiams
3.3,IrfanMuhaimin

这是我的程序.

#include <iostream>
#include <vector>
#include <fstream>
#include <string>
#include <algorithm>
using namespace std;

struct greater
{
    template<class T>
    bool operator()(T const &a, T const &b) const { return a > b; }
};

void main()
{
    vector<string> v;
    int p = 0;
    ifstream File;
    File.open("DSA.txt");
    if (!File.is_open()) return;

    string First;

    cout << "Round 1:\n";
    
        while (File >> First)
        {
            v.push_back(First);
            p++;
        }
        for (int i = 0; i < v.size(); i++)
        {
            sort(v.begin(), v.end(), greater());

            cout << v[i] << endl;
        }
}

推荐答案

最后一个for循环:

 for (int i = 0; i < v.size(); i++)
 {
     sort(v.begin(), v.end(), greater());
     cout << v[i].substr(9) << endl;
 }

如果您只想显示以CC作为第一选择的内容，则可以在循环中添加if语句:

If you want to only display ones with CC as 1st choice you can add if statement to your loop:

 for (int i = 0; i < v.size(); i++)
 {
     if (v[i].substr(0,2) != "CC") continue; 
     cout << v[i].substr(9) << endl;
 }

此外，我注意到您的代码中还有另一个问题.您不应该在每次迭代时对向量进行排序.您应该在循环之前只做一次:

Also, I noticed another problem in your code. You should not sort the vector at every iteration. You should do it only once before the loop:

 sort(v.begin(), v.end(), greater()); 
 for (int i = 0; i < v.size(); i++)
 {
     if (v[i].substr(0,2) != "CC") continue; 
     cout << v[i].substr(9) << endl;
 }

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