Vb.net regex function values between commas (",")

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I try to get all matches between two commas (","). I have so far a code but it isnt working as i expect it. The text to be searched in is the RichTextBox.Text Property.

For example i write ,5,9,12,17,4,8,11, and my regex code returns ,5,|,12,|,4,|,11,
I know what the code is doing, it is searching A-B, C-D, E-F, but i need something like A-B, B-C, C-D etc. How to modify it to return all values

VB

Me.Text = ""
Dim regex As New Regex("\,(.*?)\,")

For Each m As Match In regex.Matches(RichTextBox1.Text)
    Me.Text += m.Value & "|"
Next

What I have tried:

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Posted 4-Mar-16 4:40am

User 11061201

Updated 4-Mar-16 6:09am

v3

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3 solutions

Solution 2

This isn't mine, but I forget where I got it (it was sitting in my "useful regexes" collection under "split CSV data")

(?:^|,)(?=[^"]|(")?)"?((?(1)[^"]*|[^,"]*))"?(?=,|$)

Me? I'd use String.Split on the comma, and discard empty values rather than use a regex.

Posted 4-Mar-16 5:18am

OriginalGriff

Comments

[no name] 4-Mar-16 12:49pm

I know, but i have to use regex for the reason that i have to keep track of the match index. I have to color specific values while dealing with Richtextbox Select(index, length).
Sorry for me being a noob, i tried this "(?:^|,)" and it was catching the two endpoint commas, thus leaving no tag to catch the remaining ones. Thank you.

Solution 3

It is easier (and faster) to split the string at comma as OriginalGriff said.

Posted 4-Mar-16 6:09am

Patrice T

Comments

[no name] 4-Mar-16 12:52pm

I have to use regex to catch the tag.index which i use to color certain richtextbox text. Its of greater importance to use regex in my case. Thanks

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Richard Deeming · Accepted Answer · 2016-03-04T05:15:00

Your pattern currently consumes the leading and trailing commas, so every other value is skipped.

You need to use zero-width positive lookahead/lookbehind assertions instead:
Regular Expression Language - Quick Reference[^]

Also, it would be better to use [^\,]* rather than .*?, since you know you want to match anything except a comma.

And finally, if you're doing string concatenation in a loop, you should use a StringBuilder instead.

VB.NET

Dim regex As New Regex("(?<=\,)([^\,]*)(?=\,)")
Dim sb As New System.Text.StringBuilder()

For Each m As Match in regex.Matches(RichTextBox1.Text)
    sb.Append(m.Value)
    sb.Append("|")
Next

Me.Text = sb.ToString()