Extracting a number from a string using regex and vb.net

Question

Given a string with a numeric value in it, I need to extract that value and assign it to a variable. I use the following to accomplish that:

Dim m as Match = Regex.Match(str, "\d+")
If m.Success Then
    test = m.Groups(0).Value
End If

It works fine for string like this one:

This is a 4308 number

I get 4308 extracted. However, if the numeric value contains commas or dots:

This is a 4,308 number

Then, the value extracted is 4 instead of 4,308 or 4308.

How can I modify my regular expression to retrieve the whole number whether or not it contains commas and/or dots?

Wiktor Stribiżew · Accepted Answer · 2015-05-22 15:27:07Z

5

You can add the comma and perhaps a dot to the character class:

Dim m as Match = Regex.Match(str, "[\d.,]+")

This one is too crude since it allows strings like .,567,...

You should use

Dim m as Match = Regex.Match(str, "\d+(?:[.,]\d+)*")

It will match numbers like 1, 1,235, 2,456.56, 1,254,456.45, etc.

answered May 22, 2015 at 15:27

Wiktor Stribiżew

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