Input and output in console inside a loop

Question

I am making a C++ program to handle books. The user needs to insert the title, price and volumes for 3 books. I don't include the Book class in the code as it is not relevant with my problem.

I am stuck in the place where the user needs to input the values inside the loop. When I test the program the console keeps bugging at seemingly random times. (i.e. it shows "Give book p" instead of the full sentence and awaits for input).

I read in other answers that I should use cin.ignore() after every cin>> call in order to ignore the \n that is put on the stream when the user presses enter, but it doesn't solve my problem?

Any ideas what I am doing wrong?

#include <iostream>
#include <sstream>

using namespace std;

int main() {
    string title;
    double price;
    int volumes;

    for (int i=0; i<3;i++){
        cout << "Give book title : " << endl;
        getline (cin, title);
        cout << "Give book price : " << endl;
        cin >> price;
        cin.ignore();
        cout << "Give number of volumes : " << endl;
        cin >> volumes;
        cin.ignore();
    }

    return 0;
}

Following is an example of the console :

Give book title :
The Hobbit
The Hobbit
Give book price :
12.5
12.5
Give number of volumes :
10
10
Give book title :
Lord of the Rings
Lord of the Rings
Give book price :
12
12
Give number of volumes :
7
7
Give bo

As you can see the last sentence is cut off and the console is stuck after.

I suggest to not mix `getline` and `cin`. It's a recipe for headache as you've found. — bolov, May 16 '18 at 08:24
@thelaw Have a look at this (point 2.): https://stackoverflow.com/a/7868998/1025391 — moooeeeep, May 16 '18 at 08:35
@MichaelWalz I am using CLion IDE on Windows10. I tried it again and again. The place where the sentences are cut is seemingly random every time. Sometimes it also works. — thelaw, May 16 '18 at 08:44
@thelaw try the solution in the answer below and report back. Probbaly it won'thelp, but try anyway. — Jabberwocky, May 16 '18 at 08:45
@MichaelWalz I tried it, it wasn't working. Same problem as my code. — thelaw, May 16 '18 at 08:48
@thelaw: you asked _how else could I handle the input of a string?_ Answer: `std::cin >> title;` — Adrian W, May 16 '18 at 09:07
@AdrianW That doesn't work if the string (the title) has spaces. — thelaw, May 16 '18 at 09:11
@MichaelWalz You are right. I downloaded and tried it on Code::Blocks and it works flawlessly. — thelaw, May 16 '18 at 09:13
Your code also works flawlessly as Linux console application. May be you should just try to run it as windows console application (outside the CLion console, just by running the .exe from a command prompt) — Adrian W, May 16 '18 at 09:18

Praveen Vinny · Answer 1 · 2018-07-11T03:41:17.477

You can use std::ws as a parameter to your getline() method to achieve your objective.

The following code will serve your purpose:

#include <iostream>

int main() {
    std::string title;
    double price;
    int volumes;

    for (int i=0; i<3;i++){
        std::cout << "Give book title : ";
        std::getline(std::cin >> std::ws, title);
        std::cout << "Give book price : ";
        std::cin >> price;
        std::cout << "Give number of volumes : ";
        std::cin >> volumes;
        std::cout<<"Title: "<<title<<" costs "<<price<<" for "<<volumes<<" volumes.\n";
    }

     return 0;
}

This will produce the following output:

Give book title : Harry Potter
Give book price : 12.5
Give number of volumes : 5
Title: Harry Potter costs 12.5 for 5 volumes.
Give book title : James Anderson
Give book price : 45.6
Give number of volumes : 7
Title: James Anderson costs 45.6 for 7 volumes.
Give book title : Lucas Empire
Give book price : 34.5
Give number of volumes : 7
Title: Lucas Empire costs 34.5 for 7 volumes.

Input and output in console inside a loop

1 Answers1