Simple regex problem

[nbrege]

I have never used regular expressions before so please excuse my stupidity. I just need to check for strings that matches a particular pattern, in this case, a "J" followed by six digits. ie. "Jxxxxxx"

Here is the psuedo code:

If testString = "Jxxxxxx" Then

do some stuff

End If



Can someone show me how to code this in VB2005express? I searched through the forums but couldnt find any examples. Thanks...

 

[mskeel]

I think it would be something like (shooting from the hip):

If Regex.IsMatch(testString, "J[0-9]{6}") Then
   Do stuff
End If

J[0-9]{6} says that the string must start with J, then have 6 digits after that but I dont care what the digits are. I think you might be able to swap the 0-9 for a /d as well, but I dont remember off the top of my head. Remember youll need to import the System.Text.RegularExpression namespace at the top of the file.

 

[nbrege]

Thanks, it worked! Heres another one for you ... suppose I want to match all strings that either start with "J" followed by 6 digits (ie. "Jxxxxx") or just start with 6 digits (ie. "xxxxxx")? The leading "J" may or may not be present. Can I do that with one regex? Thanks...

 

[mskeel]

Of course!

Using the 0 or 1 operator, ?, you get "J?[0-9]{6}". So, that says you want a string with either 0 or 1 Js followed by exactly 6 digits.

I highly reccomend you get a regex tool to help you out with this stuff. Little tools like some of the ones listed here are extremely helpful. There are also a couple of links to information in general about Regex.

 

[nbrege]

Thanks yet again. One last question for you ... is it possible to specify two completely different patterns in the same regex? Is there some sort of OR operator I can use?

I will check out some of the tools you suggested so I dont have to keep bugging you about this...

 

[mskeel]

I merely suggest a helper tool so you dont have to wait for replies and can do more advanced stuff easily on your own.

The or operator, |, is exactly what you need.

So something like "(choo)|J?[0-9]{6}" would give you a string that is either "choo" or 6 digits possibly preceded by a J.

Valid strings for this regex => "J123456", "123456", "choo", ...
Invalid strings for this regex => "j123456", "J123", "cho", "12Cho", "Choo", "duh", "J12345", ...

 

[nbrege]

Thank you ... you have been a great help.