[prog] validate input

[James Sutherland]

On Sun, 21 Dec 2003 20:23:40 -0500, wolf <wolf at wolfrising.net> wrote:

> Hi, I have this C ++ code that basically adds up out of 10 students who 
> passed and who did not. You enter 1 if the student passed
> and 2 if the student failed.  It loops around so you can enter your 
> answer 10 times. All fine and good : ) However, how
> would I have it check if the user correctly entered a 1 or a 2 and if 
> they did not tell them "Invalid Entry Try Again".  The code
> as is, does seem to work correctly : ) I'm working on sample practice 
> questions and very much a beginner. Also, if there's
> a way to improve the comments, or if the indentation is incorrect, 
> please feel free to point that out as well.  I'd like to break
> any bad habits at the beginning.  Thanks : )


Try a code segment like this:


result=0;
while(result!=1 && result!=2)
{
	cout << "...";
	cin >> result;
	if (result==1)
		passes++;
	else if (result==2)
		fails++;
	else
		cout << "Bad user! Try again...";
}


Two alternatives:

Adjust the problem slightly: instead of using 1 and 2, use 1 and "anything
else". That way, there are no invalid answers!

Or count the 10 entries: set a counter to 10, and decrement it for each
valid answer. That doesn't give the immediate feedback, but does ensure
the user enters 10 valid entries.


James.