Statement after while loop isn't executed

Question

I'm having a problem with while loop. The statement after while loop isn't executed, and I've no idea why. I'm new to C++ and can't figure out this. I'm trying to take some words as input from the user and store them in a string vector, just for the sake of practice. Here's my code:

#include "stdafx.h"
#include <string>
#include <iostream>
#include <vector>

using std::vector;
using std::string;
using std::cin;
using std::cout;
using std::endl;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<string> list;
    string word;

    while( cin >> word )
    {
        list.push_back(word);
        cout << "Added " << word << endl;
    }

    cout << endl;
    cout << "Done" << endl;

    system( "PAUSE" );
    return EXIT_SUCCESS;
}

When i run this console application, i can see that the statements within while loop are executed and the messages "Added " but the message "done" is not displayed. I've tried this with by specifying other statements after while loop as well ( like a for loop fetching & display values from the same string vector ) but no statement after this while loop is executed. Only the statements before and within the while loop are executed and I've no idea why.

Answer 1

As long as you enter valid strings the loop will continue. And just entering an empty line will not work, as then the input operator will just block until it reads a non-whitespace character. You need to actually "terminate" the string by pressing CTRL-Z (the end-of-file keyboard shortcut).

---

If you want to detect empty lines and use that for termination condition, you need to use std::getline:

std::string line;
while (std::getline(std::cin, line) && !line.empty())
{
    ...
}

Answer 2

Your while loop does not end because cin will always return soemthing != 0 which means that you're trapped in an endless loop. What you need is another condition inside the loop that performs a break:

string stop_string = "exit";

while( cin >> word )
{
    if ( stop_string.compare(word) )
        break;

    list.push_back(word);
    cout << "Added " << word << endl;        
}

or you could use std::getline to detect empty lines like Joachim Pilebord suggested.