Question

ifstream myfile("input.txt"); if (myfile.is_open()) while (getline » id_read >>x_read >>y_read) go till end of file original_list.push_back (new city(id_read, x_read, y_read, id_read, false)); ++added; myfile.close(); return added; else cout << "Unable to open file"; return e;

I need help on how to correctly read the file when it exists and show error when it doesn't read

Answer 1

#include<iostream>

#include<fstream>

#include<vector>

using namespace std;

class city{

    public:

       

        city(string s, int x, int y)

        {

           

        }

};

int main()

{

    ifstream in("input.txt");

   

    // if file not able to open

    if( !in.is_open() )

    {

        cout<<"Unable to open file\n";

        exit(0);

    }

   

    vector<city *> original_list;

    int added = 0;

   

    // loop untill the end of the file

    while( !in.eof() )

    {

        string id_read;

        int x_read, y_read;

       

        // read from file

        cin>>id_read>>x_read>>y_read;

       

        // creaye objct of class city

        city *ob = new city(id_read, x_read, y_read);

       

        original_list.push_back(ob);

       

        added++;

    }

   

    in.close();

   

    return 0;

}