Visual basic validating fields

Posted by / 23-May-2016 22:50

Visual basic validating fields

Sometimes people are just trying to be funny, or they are literally trying to break your program. If the data is indeed only alphabetic letters (no symbols, no numbers or any other punctuation characters) the test succeeds and stores True inside the Name Valid variable. This is because it becomes more legible than just a normal set of numbers.

You could say that a program's testers are supposed to do this; yes, they should - nobody else should. If not, if there is even just one unallowed character that is not supposed to be there, the Match method will return False. Instead of you having to loop through each character to determine what that character is, you simply need the correct Regular Expression pattern. Clear() Surname Valid = False Else Surname Valid = True End If End Sub It is basically the exact same code for the Name box, but I just included the capability to comprehend a space character as well. People expect to enter a phone number in a format similar to this: ###-###-####.

The Format event on a data binding can be used to reformat incoming data to comply with the mask, and the Parse event can be used to reformat outgoing data to comply with the specifications of the data field. If you want full programmatic control over validation, or need to perform complex validation checks, you should use the validation events built into most Windows Forms controls.

Each control that accepts free-form user input has a Validating event that will occur whenever the control requires data validation.

A name doesn't generally contain weird symbols, and definitely not numbers. This can be from the mouse clicking inside another field, or a Tab key being pressed to navigate to the next input control. ") Else Email Valid = True 'Email is Perfect End If Else 'Not A Match To Pattern Email Valid = False 'Set Boolean Variable To False Message Box. I hope you have learned from this article and that you have enjoyed it as much as I did.

That may seem like Captain Obvious speaking, but you'll be amazed at some of the data that gets entered into a name field. I then created an If statement to determine how the input data was formatted and whether or not the data is only alphabetic.

For some reason, despite the fact it should make sure that the value is numeric before it checks whether it's within a numerical range. This is the problem I'm having, I try things like this and it still doesn't work and I just don't know why. I don't understand at what point it's trying to convert to a double. I was returning true and false the wrong way around it appears because I needed to continue the loop it needed to be true where it would usually be false in regular validation.

The masking language that is used by Masked Text Box is very flexible.

It allows you to specify required characters, optional characters, literal characters, such as hyphens and parentheses, currency characters, and date separators.

The control also works well when bound to a data source.

Input validation can take place at various times in the data entry cycle.

For example, the programmer can: The first subobjective for this chapter, verifying data entered by a user at the field level and the form level, deals mostly with the immediate validation of user input from the keyboard.

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For more information, see the WM_KILLFOCUS topic in the "Keyboard Input Reference" section, and the "Message Deadlocks" section of the "About Messages and Message Queues" topic in the MSDN library at

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