A problem with error checking

[jamesbouckley]

Hello there, I'm trying to write an interactive story game that outputs a paragraph to the console window, then asks you to make a choice what the character should do next. It works fine but I wanted to put a function in to make sure that the user inputs 1, 2, or 3. Because currently it goes a bit wrong if you don't. The current function I'm using goes as follows:

int errorcheck(int &choice)
{
	while (1)
	{
		cin >> choice;
		if((choice == 1) || (choice == 2) || (choice == 3))
		{
			return choice;
		}
		else
		{
			cout << "Please try again." << endl;
		}
	}
}

But this goes really wrong if you don't enter the right choices. Is there a convenient function that just takes in specific key presses or something instead? Thanks for any help you can offer.

P.S. I'm pretty much an absolute beginner so please use small words.

[bsonline]

I'm a beginner, too, so don't feel bad.

You could probably build this function into your display menu function, as I'm sure you will be using both at the same time.

Meanwhile, how about doing it by value instead of by each number?

while (choice <=0 || >=4)
{cout << "Please enter a valid choice." ;
cin >> choice;}

The only way to escape that loop is with a 1,2, or 3 and the only way to enter it is with a valid value. If you decide to use more than 3 choices, it is easy to modify. You can even have the number of choices modified while running by using variables.

[moorecm]

Are you aware that the argument passed to the errorcheck function is being modified?

[jamesbouckley]

Thanks for you help bsonline but unfortunately that code doesn't build. When I altered it a bit to:

while ((choice < 1) || (choice > 3))

and added a return value of "choice", it came up with the same problem as before. If you type in a load of jibberish, it outputs please enter a valid choice indefinately. This is unfortunately what I was getting with my code.
Thanks again for your help though.

[jamesbouckley]

@moorecm yes, I'm passing by reference because the choices get used later in the program.

[z05DSL3A]

you need to 'clean' cin before using it again. (read up on clear() and ignore())

[jamesbouckley]

Cheers for all your help everyone, I found the solution in the end. Copied some code from http://www.cplusplus.com/forum/articles/6046/
in the end. Modified it a bit. Now all is well.