How to get results from txt file and then sum it?

Question

I'm writing an electronic voting system and in the end, I want to show on the screen percentage results, not the numbers for candidates. So I collected everything in a file. It looks like this: "results.txt"

Jessica: 2

Amanda: 3

Michael: 0

Sam: 0

Alex: 1

Nancy: 0

and after that can I take these numbers to sum them and convert to a percentage? I don't know how to realize that.

This is the part of the program:

ofstream VotingResults ("results.txt", ios::app);

cout<<"Please enter a number for whom you give your vote: ";

        cin >> choice;

          switch (choice)
          {
                 case 1: 
                      Vote(Jessica);
                      cout<<"Press any button to get the results";
                      break;
                 case 2:
                      Vote(Amanda);
                        cout<<"Press any button to get the results";
                      break;
                 case 3:
                      Vote(Michael);
                      cout<<"Press any button to get the results";
                      break;
                 case 4:
                        Vote(Sam);
                        cout<<"Press any button to get the results";
                        break;
                case 5:
                        Vote(Alex);
                        cout<<"Press any button to get the results";
                        break;
                case 6:
                        Vote(Nancy);
                        cout<<"Press any button to get the results";

                        break;
                default:
                    cout<<"Invalid number! Press any button to get the results";
                        break;
                    }

    VotingResults.open("results.txt");
          VotingResults << "Jessica: " << Jessica << endl
                 << "Amanda: " << Amanda << endl
                 << "Michael: " << Michael << endl
                 << "Sam: " << Sam << endl
                 << "Alex: " << Alex << endl
                 << "Nancy: " << Nancy << endl;
          VotingResults.close();


void Vote(int &a)
{
     a += 1;
     cout << "\n\t\tThank you for your vote! ";
}

Do you know how to convert individual values that comprise a total into percentages, purely as a mathematical process? If you don't, then this has nothing to do with C++ or programming, you need to learn how to do that first. If you do, then you simply do the same thing in C++. What exactly is your specific question, related to C++? — Sam Varshavchik, Oct 23 '19 at 20:51
Warning: `ofstream VotingResults ("results.txt", ios::app);` opened `VotingResults`. `VotingResults.open("results.txt");` opens the file again. You probably don't want to do that. — user4581301, Oct 23 '19 at 21:02
Need more code. Is `Jessica` a variable? Is it an `enum`? Is it a constant? — Thomas Matthews, Oct 23 '19 at 22:16

score 0 · Answer 1 · answered Oct 23 '19 at 22:24

I recommend using std::map for this:

std::map<std::string, int> database;
//...
std::string voter_name;
std::int    voter_number;
while (std::getline(Voting_Results, voter_name, ':'))
{
   Voting_Results >> voter_number;
   if (database.find(voter_name) != database.end())
   {
       database[voter_name]++;
   }
   else
   {
       database[voter_name] = 0;
   }
}

If the name exists in the map, the value field is incremented. The value field will represent the number of votes (or occurrences).

The number associated with the voter is read, but not used, in order to keep the reading synchronized.

How to get results from txt file and then sum it?

1 Answers1