C# Validation for specific input

Question

I'm kinda new to this thread, but in short summary i'm having trouble with a small validation issue. Basically, i'm attempting to make a simple validation program that will collect a user's input and then determine if the input is valid in terms of, input being correctly implemented, the number being positive, and the number having to be either 0, 1, 2, 3, 4 or 5.

The overall program runs, but the issue i'm facing is every form of input is deemed an error, thus displaying my error statement, even if it is a valid input like 5 for example. I feel like there is a small mistake,i have made that is causing this, So is there any suggestions?

 int user_input;
 int count = 0;
 do
 {
    Console.Write("\n\nUser Input:"

    if ((int.TryParse(Console.ReadLine(), out user_input) == false)||(user_input < 0 || user_input != 0 ||user_input != 1 || user_input != 2
                || user_input != 3 || user_input != 4 || user_input != 5)) 
    {

       Console.WriteLine("Error : the action entered is not a valid number.");
       count = 0;
    }
    else
       count = 1;

Artem Kulikov · Accepted Answer · 2015-08-22 07:01:29Z

4

Your mistake is because you use OR operator. For example user print 3. In your statements one condition return false (input != 3), but all others return true.. That's why you always go into if condition..

You can use AND operator, but I can recommend you to simplify your condition. It will be more understandable and readable:

var count = 0;
do
{
   Console.Write("\n\nUser Input:");

   int user_input;
   if ((int.TryParse(Console.ReadLine(), out user_input) == false) || (user_input < 0 || user_input > 5))
   {

      Console.WriteLine("Error : the action entered is not a valid number.");
      count = 0;
   }
   else
      count = 1;
} 
while (count != 1);

edited Aug 22, 2015 at 7:01

answered Aug 22, 2015 at 6:55

Artem Kulikov

2,29421 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

autistic Over a year ago

Just one language nitpick: It's not necessarily a mistake to use the OR operator, though it is a mistake to misuse the OR operator.

Philip Newton Over a year ago

Thanks for the quick response, implemented perfectly!

Giorgi Nakeuri · Accepted Answer · 2015-08-22 07:28:13Z

1

You already got an answer about the problem with predicate logic. But you can even more simplify with linq like:

var count = (new string[]{"1","2","3","4","5"}).Contains(Console.ReadLine()) ? 1 : 0;

answered Aug 22, 2015 at 7:28

Giorgi Nakeuri

35.9k8 gold badges50 silver badges78 bronze badges

Collectives™ on Stack Overflow

C# Validation for specific input

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related