Making RegEx Match Bold - VB.NET

Question

This is my current RegEx: \\[b\\](.*?)\\[/b\\]

That works perfectly fine, it replaces exactly what I want it to. But, I'm trying to figure out how to make it replace the string between [b][/b] with a bold string, but the actual text stays the same.

Example string: [b]This is an example![/b]

Desired output: This is an example!

I'm using VB.NET and this is what I currently have:

Dim reg As New Regex("\[b\](.*?)\[/b\]")
Dim str As String = String.Empty
For Each m As Match In reg.Matches(MainBox.Text)
  str = reg.Replace(MainBox.Text, "test")
Next

Preview.Show()
Preview.RichTextBox1.Text = str
Preview.Size = New Size(Preview.MaximumSize.Width, Preview.MaximumSize.Height)

Answer 1

You need to set the start of the selection, and set the attributes of the text before inserting it.

Preview.RichTextBox1.SelectionStart = Preview.RichTextBox1.Text.Length
Preview.RichTextBox1.SelectionFont = New Font("Tahoma", 12, FontStyle.Bold)
Preview.RichTextBox1.SelectedText = str