Solved

Very newb question about std::cin

Posted on 2003-11-19
5
452 Views
Last Modified: 2010-04-02
I used:

std::cin >> someStdStringVar;

and then I follow it up with another prompt and

std::cin.getline(someCharArray,maxCharsToExtract);

If you've used std::cin frequently you'll know that this won't work. There are still characters left in the buffer (2 in my case) and my bet is that they are the \r\n pair not stored into someStdStringVar previously.

The only way I managed to get them out of there was to add another getline() call before the one I'm interested in.

I tried std::cin.seekg(0,std::ios_base::end); and also std::cin.ignore(INFINITE); before the call to getline() but both caused the following call to getline() to fail to block while waiting for input and filled the buffer with nothing.

I don't mind calling getline() and extra time, but it seems crude. Why is seekg() not working as I expect it to?

thanks,
-Sandra

0
Comment
Question by:Sandra-24
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 
LVL 13

Accepted Solution

by:
SteH earned 300 total points
ID: 9785392
I would guess that
std::cin.ignore (INFINITE, '\n');
should work. From cin I wouldn't expect any EOF since it is a stream but not a file.
0
 
LVL 3

Author Comment

by:Sandra-24
ID: 9785466
Nope does the same as the rest :(

Using cin is not as simple as it looks.
0
 
LVL 1

Expert Comment

by:Hoegje
ID: 9785481
maybe this will help :

std::cin.flush(); // flush the complete stream

Not sure though !
0
 
LVL 17

Assisted Solution

by:rstaveley
rstaveley earned 200 total points
ID: 9786071
This works for me, Sandra:
--------8<--------
#include <iostream>
#include <limits>

int main()
{
        std::string str1,str2;
        using std::cin;
        const int INFINITE = std::numeric_limits<int>::max();

        cin >> str1;
        cin.ignore(INFINITE,'\n');
        getline(cin,str2);
        std::cout << "str1 [" << str1 << "]\nstr2 [" << str2 << "]\n";
}
--------8<--------

Can you post a simple example of your problem?
0
 
LVL 3

Author Comment

by:Sandra-24
ID: 9789633
You guys are right. The trouble was that I didn't define INFINITE in my program. Ordinarily that would prevent it from compiling, but it worked because a define of INFINITE does exist 0xFFFFFFFF which proabably wrapped to a negative number (or so I'm guessing). At any rate it's working now, thanks!
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article will show you some of the more useful Standard Template Library (STL) algorithms through the use of working examples.  You will learn about how these algorithms fit into the STL architecture, how they work with STL containers, and why t…
Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

696 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question