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[smashapps]

Regular Expressions can be confusing for many people but when you actually get your head around it it isn't that bad I am still learning it myself but I want to show you guys something thats easy to do

Ok so what I am going to show you is I have a textbox and an error provider and a button.

If the textbox contains anything that ISNT a number then the error provider will tell you that you can only use numbers

when you press the button if you only used numbers then a msgbox will pop up saying it was only numbers

Code:

Code: Select all

Imports System.Text.RegularExpressions
Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim Numregex As New Regex("^[0-9]*$")
        If Numregex.IsMatch(TextBox1.Text) Then
            ErrorProvider1.SetError(TextBox1, [String].Empty)
            MsgBox("It only contained numbers, good")
        Else
            ErrorProvider1.SetError(TextBox1, "You can only use numbers")
        End If
    End Sub

    Private Sub TextBox1_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox1.TextChanged
        Dim Numregex As New Regex("^[0-9]*$")
        If Numregex.IsMatch(TextBox1.Text) Then
            ErrorProvider1.SetError(TextBox1, [String].Empty)
        Else
            ErrorProvider1.SetError(TextBox1, "You can only use numbers")
        End If
    End Sub
End Class

The "^[0-9]*$" is the expression we are using. the ^ indicates the beginning of the input, and the $ indicates the end of the input.

the [0-9] is what it is looking for, and the * indicates that it can match any amount of numbers 0 to what ever number you want, for example it doesnt matter if you have 094096409640 or 358748574 as long as it is a number it is fine.

[MrAksel]

Really nice, i have never seen any tut like this earlier!

[Axel]

Don't forget to mention that [] matches every character and $ is the end of a string
I think I might do some tutorials about regex :P

[smashapps]

yes I mentioned $ was the end of the input and thanks

[2cool4cereal2]

I think you could turn this around and make it so numbers are not allowed. That'd also be good, nice tutorial.

[smashapps]

Thanks and yes there is soo many things you can do with Regular expressions you can use them to find certain input patterns for example find a postcode or a phone number pretty cool

[renegade809]

This is nice, but would you be able to do a tut that's a little more advanced?
I am trying to figure out how to use it with a WebBrowser Control. I suck at httpwebrequest, and I have only used Regex one time, to use it for scraping proxies.

[smashapps]

I have stopped doing the regex tutorials sorry mate but you can find alot of great examples with a simple Google search =)

Hope you find what you need