Trouble with Arrays

[Dylan 256]

So I am trying to write a code that can take the names and scores of a certain number of people that is decided upon by the user. I then have to put it in order of highest score to lowest score which I know how to do I just do not have the code for it below. The problem I am having at the moment is that I can not get the arrays to accept user input. If I get rid of the array that is for the names then the code works fine and stores the correct number of numerical values. I just can not figure out how to get it to store names in an array repeatedly. Can somebody explain what the problem might be please?

  // Example program
#include <iostream>
#include <string>
using namespace std;

int main()
{
    int size;
    cout << "How many records will be entered?" << endl;
    cin >> size;

    char name [size];
    float score [size];
    
    for (int i=0; i<size; i++)
    {
        cout<< "Enter the names and scores of the students." << endl;
        cin >> name [i];
        cin >> score [i];
    }   
}

[E0p9LyTq]

You can't create a C-style array of variable size at run, you need a C++ container for that. A vector works well.

Creating a structure to contain a student's name and score makes it easier to deal with the data and the vector.

#include <iostream>
#include <string>
#include <vector>

struct student_data
{
   std::string name;
   float score;
};

int main()
{
   int size;
   std::cout << "How many records will be entered? ";
   std::cin >> size;

   student_data data;
   std::vector<student_data> students;

   for (int loop = 0; loop < size; loop++)
   {
      std::cout << "Enter the names and scores of the students: ";
      std::cin >> data.name;
      std::cout << "Enter the student's score: ";
      std::cin >> data.score;

      students.push_back(data);
   }
   std::cout << '\n';

   for (size_t loop = 0; loop < students.size(); loop++)
   {
      std::cout << students[loop].name << "\t" << students[loop].score << '\n';
   }
}

How many records will be entered? 3
Enter the names and scores of the students: joe
Enter the student's score: 1.5
Enter the names and scores of the students: mary
Enter the student's score: 2.7
Enter the names and scores of the students: frank
Enter the student's score: 3.9

joe     1.5
mary    2.7
frank   3.9

[Dylan 256]

Oh ok that makes sense, thank you. Although I do not know how to use vectors very well so I have a follow up question. If I wanted to sort the values being entered so that they would be in descending order from highest score to lowest score how would I do that now?

[E0p9LyTq]

If you wanted to sort then you could use a std::map or std::multimap container. No need for the structure if using one of those containers.

You could use a student's name as the mapped element and their score as the key value.

A map/multimap automatically sorts the container, based on the key value.

http://www.cplusplus.com/reference/map/map/

Since it is likely to have the same score for more than one student, a multimap would work

http://www.cplusplus.com/reference/map/multimap/

[Thomas1965]

If you want to stick with a vector just use std::sort to sort it.
http://www.cplusplus.com/reference/algorithm/sort/

[E0p9LyTq]

You are working with two different data types for each student record, you could use std::pair.

Creating a few custom comparison functions for std::sort you can sort by name or score, ascending or descending order:

#include <iostream>
#include <string>
#include <vector>
#include <utility> // for std::pair
#include <limits>
#include <algorithm> // for std::sort

bool sort_pairfirst_desc(std::pair<std::string, double> i, std::pair<std::string, double> j)
{
   return (i.first > j.first);
}

bool sort_pairsecond_asc(std::pair<std::string, double> i, std::pair<std::string, double> j)
{
   return (i.second < j.second);
}

bool sort_pairsecond_desc(std::pair<std::string, double> i, std::pair<std::string, double> j)
{
   return (i.second > j.second);
}

int main()
{
   std::vector<std::pair<std::string, double>> students;
   std::pair<std::string, double> student;

   while (true)
   {
      std::string name;

      std::cout << "Enter the name of the student (QUIT to quit): ";
      std::getline(std::cin, name);
      if ("QUIT" == name)
      {
         break;
      }

      double score;
      std::cout << "Enter the student's score: ";
      std::cin >> score;
      
      student = std::make_pair(name, score);
      students.push_back(student);

      // flush the input buffer
      std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
   }
   std::cout << '\n';

   std::cout << "The unsorted list:\n";
   for (auto it : students)
   {
      std::cout << it.first << ":\t"<< it.second << '\n';
   }

   std::sort(students.begin(), students.end());

   std::cout << "\nThe default sorted list:\n";
   for (auto it : students)
   {
      std::cout << it.first << ":\t" << it.second << '\n';
   }

   std::sort(students.begin(), students.end(), sort_pairfirst_desc);

   std::cout << "\nThe descending name sorted list:\n";
   for (auto it : students)
   {
      std::cout << it.first << ":\t" << it.second << '\n';
   }

   std::sort(students.begin(), students.end(), sort_pairsecond_asc);

   std::cout << "\nThe ascending score sorted list:\n";
   for (auto it : students)
   {
      std::cout << it.first << ":\t" << it.second << '\n';
   }

   std::sort(students.begin(), students.end(), sort_pairsecond_desc);

   std::cout << "\nThe descending score sorted list:\n";
   for (auto it : students)
   {
      std::cout << it.first << ":\t" << it.second << '\n';
   }
}

Enter the name of the student (QUIT to quit): joe d'ragman
Enter the student's score: 4
Enter the name of the student (QUIT to quit): joe rogan
Enter the student's score: 12
Enter the name of the student (QUIT to quit): mary poppins
Enter the student's score: 3
Enter the name of the student (QUIT to quit): frank furter
Enter the student's score: 8
Enter the name of the student (QUIT to quit): QUIT

The unsorted list:
joe d'ragman:   4
joe rogan:      12
mary poppins:   3
frank furter:   8

The default sorted list:
frank furter:   8
joe d'ragman:   4
joe rogan:      12
mary poppins:   3

The descending name sorted list:
mary poppins:   3
joe rogan:      12
joe d'ragman:   4
frank furter:   8

The ascending score sorted list:
mary poppins:   3
joe d'ragman:   4
frank furter:   8
joe rogan:      12

The descending score sorted list:
joe rogan:      12
frank furter:   8
joe d'ragman:   4
mary poppins:   3

(If this program gets much larger the layout could benefit from putting portions of the code in main() into other functions, making it easier to maintain and read.)