Displaying all data stored in file is showing an extra data,using loop in C++ File handling

Question

I am making a contact management system on console. I am at beginner level. I have stored data in file using file handling[class : newContact, function : void newcIn (in my code)]. When i display all data stored in my file, it shows an extra entity. I have used while loop with condition !read1.eof().`

    //create new contact
#include<iostream>
#include<string>
#include<fstream>

using namespace std;
 
ofstream write1, write2;
ifstream read1, read2;
 
class newContact {
      protected:
        string name,num;

      public:
        newContact() {
            name="No name";
            num="1234567891011";    
        }

        void newcIn() {
            write1.open("contact.txt",ios::out|ios::app);
            
            cout << "Enter name : ";
            cin.ignore();
            getline(cin,name);
            cout << "Enter number : ";
            getline(cin,num);
            
            write1 << name << endl;
            write1 << num << endl;
            
            write1.close();
            system("CLS");
        }

        void dispAll() {
            read1.open("contact.txt",ios::in);
            
            while (!read1.eof()) {
                   getline(read1,name);
                   getline(read1,num);
            
                   cout << "Name : " << name << endl;
                   cout << "Number : " << num << endl;
            }
            
            cout << "\n\n--------\n" << endl;
            read1.close();
        }
};

class whatTodo : public newContact {
      public:
     
        void mainMenuWorking() {    
             int mainMenuChoice=0;

             do {
                cout << "Enter your choice : " << endl;         
                cout << "1.New contact\n2.Display All contacts\n3.Exit"<<endl;
                cin >> mainMenuChoice;

                switch (mainMenuChoice) {
                case 1:
                        system("CLS");
                        newcIn();
                        break;
                case 2:
                        system("CLS");
                        dispAll();
                        break;  
                default:
                        cout << "Invalid input" << endl;        
            }
        } while (mainMenuChoice!=0);
    }
};

int main() {
    newContact obj;
    whatTodo obj2;
    
    obj2.mainMenuWorking();
    return 0;
}

`while(!read1.eof())` [https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons](https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons) — drescherjm, Sep 18 '20 at 16:53
Does this answer your question? [Why is iostream::eof inside a loop condition (i.e. \`while (!stream.eof())\`) considered wrong?](https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons) — drescherjm, Sep 18 '20 at 16:53

Build Succeeded · Answer 1 · 2020-09-19T12:35:14.997

This is happening due to the extra line empty line is inserted by newcIn(). You can remove endl after the contact number writing. It should work for you.

    while (!read1.eof())
    {
        string name1, num1;
        getline(read1, name1);
        getline(read1, num1);

        if (!name1.empty() && !num1.empty())
        {
            cout << "Name : " << name1 << endl;
            cout << "Number : " << num1 << endl;
        }
    }

Due to extra empty line file return empty data but class variable return whatever they have. So, better to add local variable to read data from file.

Suggestion: You can rewrite the newCIn() which can insert the data pair correctly without adding extra linebreak.

Displaying all data stored in file is showing an extra data,using loop in C++ File handling

1 Answers1