Read file with separation in C++

Question

I have a script which reads text file into a vector.

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

struct Items
{
    string Name;
    int Number1;
    double Number2;
};

int main()
{
    ifstream file("file4.txt"); 
    vector<Items> player_data;
    Items player_info;
    while (file >> player_info.Name >> player_info.Number1 >> player_info.Number2) { 
        player_data.push_back(player_info);
    }

    for (auto &i : player_data) {
        std::cout << i.Name << ", " << i.Number1 << ", " << i.Number2 << endl;
    }
}

The file4.txt contains as follows:

Wogger Wabbit
2
6.2
Bilbo Baggins
111
81.3
Mary Poppins
29
154.8

How can I display the data properly? How could I give the separation which is a line break ('\n')?

Answer 1

You have a few problems with your code; this solution works but it's not elegant. I'm sure the people here can give you or direct you to a more elegant one :)

First - after opening a file you need to check if it is open

Second - it is better to use std::getline() to read from the file because it gets the whole line. The >> stops when it gets to space.

Also, try not to use using namespace std

EDIT

added print of the error if the file doesn't open

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <cerrno>
#include  <cstring>

using namespace std;

struct Items
{
  string Name;
  int Number1;
  double Number2;
};

int main()
{
  ifstream file("text4.text");
  if(!file.is_open()) // <- check if file opened correctly
  {
    std::cout << std::strerror(errno); // <- print the reason why the file didnt open 
    return 0;
  }
  vector<Items> player_data;
  Items player_info;
  std::string line;
 while(std::getline(file,line)) // <-- read lines and stop when the file is finished 
 {
   player_info.Name = line;
   std::getline(file,line);
   player_info.Number1 = stoi(line);
   std::getline(file,line);
   player_info.Number2 = stod(line);
   player_data.push_back(player_info);
 }


  for (auto &i : player_data) {
    std::cout << i.Name << ", " << i.Number1 << ", " << i.Number2 << endl;
  }
}

Answer 2

From your description, I am assuming you want to print the outputs line by line. So use '\n' instead of comma:

std::cout << i.Name << "\n" << i.Number1 << "\n" << i.Number2 << endl;

Answer 3

You can solve your issue in the following way -

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

struct Items {
    string Name;
    int Number1;
    double Number2;
};

int main() {
    ifstream file("file4.txt");
    vector<Items> player_data;
    Items player_info;
    while (getline(file,player_info.Name)) {
        file>>player_info.Number1>>player_info.Number2;
        player_data.push_back(player_info);
        file.ignore();

    }
    file.close();
    for (auto &i : player_data) {
        cout << i.Name << ", " << i.Number1 << ", " << i.Number2 << endl;
    }
}

Now let's investigate what's the catch is here.

1. First of all, your name can contain blank space between them and you can't take input a string with empty space using >> operator. You have to you getline() function to take input string with empty spaces. This function take input the whole line of the input file as a string.
2. Secondly, your other two inputs are integers or other primitive data types so you can take input them using >> operator. In the above code, these two input is inside the while loop.
3. Lastly and most important file.ignore(). >> operator terminates input when it encounters a blank space ' ', newline '\n' character. So after taking the input of player_info.Number2 there is a newline character in the input file so >> operator stop here but the newline character remains in the input buffer and getline() function is very sensitive to newline and blank space character so this creates a problem. So you have to somehow remove or ignore the buffer's newline character. file.ignore() do this job for you.