I am trying to validate user input into a textbox to make sure that the user has entered a number that is in a decimal format. 15.1; 5.1 etc.) I think that I am close on the code below in terms of validating that the textbox input is a number but I am not sure how to validate the decimal.
Private Sub Text Box1_Key Press(By Val sender As Object, By Val e As System.
by using the isnumeric you get what validation I think you are looking for.. And to answer your question; no, there is not reason to validate on each character all I am trying to do is validate format.
My surname contains a space and it can get quite frustrating if I am not allowed to enter my correct surname, or that I have to edit my surname not to include a space. In certain cases the international dialling code will also need to be supplied. Compiled _ ) Dim bln Possible Match As Boolean = re Email. Text) If bln Possible Match Then 'Check If Entered Email Is In Correct Format If Not txt Email.
So, what I am trying to say is: make sure you understand other cultures, or be aware of people with uncommon names. Using Regular expressions here, is basically the standard, even though it is a bit messy. Focus() 'Return Focus End If End Sub Here, I created a separate function to do all the work.
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.
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.
Because everyone has a different way of doing things, my methods might not be 100% the same as your methods.
This is why I decided to make use of Regular Expressions here within this article.
Also, the more tests you are performing, the slower your app might become. For more information regarding Regular Expressions, you are welcome to look at these two MSDN articles: Because it is always easy to learn by doing things practically, you will be creating an app that makes use of Regular Expressions to determine valid input. NET application and design the form to resemble Figure 1. Obviously this only works for the formatting of the email.
Figure 1 - These objects will determine if all our data is valid or not. Clear() 'Clear Text Box Name Valid = False 'Boolean = False Else Name Valid = True 'Everything Fine End If End Sub Easy one to start with. Focus() 'Set Focus To Text Box End If End Sub Private Sub txt Email_Lost Focus(sender As Object, e As System. Lost Focus Validate Email() 'Check Email Validity End Sub The expression may look horrible to the layman's eye, but look closer. To check if the user has entered an email that actually exists, you will have to find a different way such as to send a of some sorts.
New() 'This call is required by the Windows Form Designer.
Label 'Required by the Windows Form Designer Private components As System. Container 'NOTE: The following procedure is required by the Windows Form Designer 'It can be modified using the Windows Form Designer.
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: ###-###-####.