CODEWITHSUNDEEP
regexvb.net.net-4.0
KelvZhan
KelvZhan

Reputation: 140

Regex to get text between two strings

I want to get dynamic six seven-digit numbers as shown below:

id="tid_3660328">

and append them to the end of TextBox1.

In other words, I want to get the number: 3660328

From between: id="tid_

and: ">

My question is how I could do this in VB.NET. My first thought was "regex", which is a topic I have zero experience on. I appreciate the help.

Note: I was thinking I could use the code here but with my own regex: https://stackoverflow.com/a/9332731

Upvotes: 2

Views: 8455

Answers (2)

Steven Doggart
Steven Doggart

Reputation: 43743

This is a good place for using RegEx.

If you only want to find numbers that are exactly seven digits you could use this RegEx pattern:

id="tid_(\d{7})">

Or, if you don't care how many digits it is, you could use this pattern:

id="tid_(\d+)">

Here's what the pattern means:

  • id="tid_ - Matching strings must begin with this text
  • (...) - Creates a group so that we can later access the value of just this part of the match.
  • \d - Any numeric digit character
  • {7} - Seven numeric characters in a row
  • "> - Matching strings must end with this text

In the second pattern, the +, which replaces the {7} just means one-or-more instead of exactly seven.

In VB.NET, you can search an input string using a RegEx pattern, like this:

Public Function FindNumbers(input As String) As List(Of String)
    Dim numbers As New List(Of String)()
    Dim pattern As String = "id=""tid_(\d{7})"">"
    For Each i As Match In Regex.Matches(input, pattern)
        numbers.Add(i.Groups(1).Value)
    Next
    Return numbers
End Function

Notice that in the string literal in VB, you have to escape the quotation marks by doubling them. You'll also notice that, instead of using i.Value, we are using i.Groups(1).Value. The reason is that i.Value will equal the entire matched string (e.g. id="tid_3660328">), whereas group 1 will equal just the number part (e.g. 3660328).

Update

To answer your question below, to call this function and output it to a TextBox, you could do something like this:

Dim numbers As List(Of String) = FindNumbers("id=""tid_3660328"">")
Text1.Text = String.Join(Environment.NewLine, numbers.ToArray())

Upvotes: 4

gpmurthy
gpmurthy

Reputation: 2427

Consider the following Regex...

(?<=tid_).*?(?=\"\>)

Explanation:

  • (?<=tid_) : Match the Prefix tid_ but exclude it from the capture
  • .*? : Any Character, any number of repetitions, as few as possible
  • (?=\">) : Match the suffix "> but exclude it from the capture

Upvotes: 2

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