Regular expression for validating numbers only vincent gallo dating
Since a version of this control hasn't been provided for use in Windows Forms, it makes a great example of a custom control that you can build—a Windows Form Text Box that validates its contents against a regular expression.To create my validating Text Box, I will have to work through a few different steps.NET: Introduction Sample 1a: Adding Regular Expression Validation to the Text Box Control A Short Discussion on Regular Expressions What Do I Need to Build?Sample 1b: Adding Regular Expression Validation an Alternative Way Summary Two samples are covered in this article: creating a custom Text Box that performs regular expression validation, and creating an extender provider that uses a different method to perform the same regular expression validation.This notation requires that international phone numbers include a leading plus sign (known as the ), and allows only spaces to separate groups of digits. EPP is a relatively recent protocol (finalized in 2004), designed for communication between domain name registries and registrars.Although the tilde character (~) can appear within a phone number to indicate the existence of an additional dial tone, it has been excluded from this regular expression since it is merely a procedural element (in other words, it is not actually dialed) and is infrequently used. It is used by a growing number of domain name registries, including .
Although this class describes a Windows Form control, adding a new property is no different than adding it to any other Microsoft Visual Basic® . Following the examples for that reference documentation, I can create a new Reg Ex object specifying the Regular Expression property in the constructor and then use that object to check if the Text Box contents match the expression: 'added a Imports System. Regular Expressions to the 'top of the class to simplify the code Private Function Is Valid(By Val Contents As String) As Boolean Dim my Reg Ex As New Regex(Regular Expression) Dim my Match As Match my Match = my Reg Ex. Success End Function If I could try out the control at this point I would realize that this code isn't correct, because it will return True if a match is found anywhere inside the string.
For this control, there are two properties: Valid and Regular Expression. Category attribute is what you will use to specify the appropriate category, but note that it just takes a string as an argument, so make sure you spell the category name correctly: Figure 1.
I am going to put Regular Expression in the Behavior category, but there is no real restriction on where you put a specific property; you can even create your own category. You can use any category name you wish and it will appear as a section of the property window. Description attribute accepts a string as an argument that is then displayed whenever that property is selected in the Properties window: Valid, unlike Regular Expression, is not very useful at design time (it is read-only and calculated based on the contents of the Text Box), so I do not want it to appear in the Properties window in any category.
With all of this in mind, let’s look at the regular expression again after breaking it into its pieces. : # Group but don't capture: [0-9] # Match a digit. ITU-T Recommendation E.123 (“Notation for national and international telephone numbers, e-mail addresses and web addresses”) can be downloaded at
Because this version is written using free-spacing style, the literal space character has been replaced with ^ # Assert position at the beginning of the string. ITU-T Recommendation E.164 (“The international public telecommunication numbering plan”) can be downloaded at RFC 5733 defines the syntax and semantics of EPP contact identifiers, including international phone numbers. Techniques used in the regular expressions in this recipe are discussed in Chapter 2.
Since I haven't added any of my own code, this new control would look and behave exactly like a regular Text Box; inheriting does not change anything until you start adding code or attributes.