better understanding of getline() and cin

Question

Trying to get some basic understanding of console functionalities. I am having issues so consider the following...

#include "stdafx.h"
#include<iostream>
#include<conio.h>

using namespace std;

/*
This is a template Project
*/

void MultiplicationTable(int x);

int main()
{

    int value = 0;

    printf("Please enter any number \n\n");
    getline(cin, value);

    MultiplicationTable(value);


    getchar();


    return 0;
}

I actually based this off code from http://www.cplusplus.com/doc/tutorial/basic_io/ . My IDE is not recognizing getline() so of course when I compile the application. I get an error

'getline': identifier not found

Now take a look at this code

#include "stdafx.h"
#include<iostream>
#include<conio.h>

using namespace std;

/*
This is a template Project
*/

void MultiplicationTable(int x);

int main()
{

    int value = 0;

    printf("Please enter any number \n\n");
    cin>>value;

    MultiplicationTable(value);


    getchar();


    return 0;
}

When I execute this line of code the console window opens and immediately closes. I think I a missing something about cin. I do know that it delimits spaces but I don't know what else. what should I use for input to make my life easier.

Answer 1

The function getline() is declared in the string header. So, you have to add #include <string>. It is defined as istream& getline ( istream& is, string& str );, but you call it with an int instead of a string object.

About your second question:

When I execute this line of code the console window opens and immediately closes

There is probably still a '\n' character from your input in the stream, when your program reaches the function getchar() (which I assume you put there so your window doesn't close). You have to flush your stream. An easy fix is, instead of getchar(), add the line

 int c;
 while((c = getchar()) != '\n'){} 

This will flush your stream until the next line-break.

Remark: conio.h is not part of the c++ standard and obsolete.

Answer 2

The getline function reads strings, not integers:

#include <string>
#include <iostream>
using namespace std;

int main() {
    string line;
    getline( cin, line );
    cout << "You entered: " << line << endl;
}