How to find out what cin.getline() returns?

[meesa]

Okay, so I have this line of code

cin.getline(var.line1,50);

The rest of the code doesn't matter.

I know that getline() returns either eofbit, failbit, or badbit. My question is how do I find out what is returned. I can't find anything about this on Google/Bing Search.

Thanks!

[firedraco]

I don't think it does:

Return Value
The function returns *this.

Errors are signaled by modifying the internal state flags

[meesa]

Errors are signaled by modifying the internal state flags

So can I get the internal state flags then?

What I want to do, is make sure the user doesn't enter a string too long. Which means I need to be able to detect if there is a failbit.

[firedraco]

cin.failbit(), cin.eof(), etc

[meesa]

Thanks! That gets me into the loop. Now I face a continuous loop

cin.getline(var.line1,50);
while(cin.failbit){
    cout<<"Error: Your line is too long.\nPlease enter a shorter line: ";
    cin.getline(var.line1,50);
}

That there, I enter a string too long on the first time, and after that, the while loop repeats infinitely. Any clues why?

Note: If I put cin.failbit() rather then cin.failbit I get an error.

[firedraco]

You have to clear the stream (to reset the error bits)

[mcleano]

cin.getline() doesn't clear the stream like getline() does so as firedraco said, you need to clear it yourself.

[Chewbob]

The function is cin.fail() rather than cin.failbit(). Or you could do !cin.good().

[Zhuge]

I'm pretty sure just !cin works too.

[meesa]

You have to clear the stream (to reset the error bits)

Thank you, used cin.clear(ios::goodbit);

cin.getline() doesn't clear the stream like getline() does so as firedraco said, you need to clear it yourself.

How do you use getline() alone? I get an error if I remove the cin.

The function is cin.fail() rather than cin.failbit(). Or you could do !cin.good().

Ahh, well that helps! Much shorter then cin.rdstate()==ios::failbit
Don't want to use !cin.good() because I don't want to display for the user to enter a shorter line if it is a fatal error, but good to know!


Overall, here is the full while statement. Plus the first cin.getline()

cin.getline(var.line1,50);
while(cin.fail()){
  cout<<"Error: Your line is too long.\nPlease enter a shorter line: ";
  cin.clear(ios::goodbit);
  cin.ignore(99,'\n');
  cin.getline(var.line1,50);
}

Note: For future people reading this, you can also use cin.clear(cin.good()), which is 2 characters shorter. :)

Thanks a lot for your help!