Remove Punctuation From StringRemove all punctuation characters from the start and end of strings. Use Char.IsPunctuation.
This page was last reviewed on Mar 19, 2022.
Remove punctuation. In programs, strings often contain unneeded characters. In VB.NET there are many ways to remove punctuation characters from strings.
IsPunctuation. Here we use the Char.IsPunctuation function. It handles all punctuation characters. It is built into .NET and returns a Boolean telling us whether the char is punctuation.
Example. We introduce TrimPunctuation. This counts punctuation characters at the start and the end. We use 2 for-loops and call Char.IsPunctuation to check each character.
Substring We use the Substring function to eliminate all the punctuation characters we counted. We use the counts as offsets.
Finally We loop over the string values and display the trimmed version. This helps us check correctness of the method.
Module Module1 Sub Main() Dim values() As String = {"One?", "--two--", "...three!", "four", "", "five*"} ' Loop over strings and call TrimPunctuation. For Each value As String In values Console.WriteLine(TrimPunctuation(value)) Next End Sub Function TrimPunctuation(ByVal value As String) ' Count leading punctuation. Dim removeFromStart As Integer = 0 For i As Integer = 0 To value.Length - 1 Step 1 If Char.IsPunctuation(value(i)) Then removeFromStart += 1 Else Exit For End If Next ' Count trailing punctuation. Dim removeFromEnd As Integer = 0 For i As Integer = value.Length - 1 To 0 Step -1 If Char.IsPunctuation(value(i)) Then removeFromEnd += 1 Else Exit For End If Next ' Remove leading and trailing punctuation. Return value.Substring(removeFromStart, value.Length - removeFromEnd - removeFromStart) End Function End Module
One two three four five
Discussion. There are other ways to remove punctuation—Trim() can remove a set of characters. You can call Trim with an array of punctuation characters and it will work in the same way.
However Using a large array may be inefficient. And you may omit characters that Char.IsPunctuation detects.
Regex Another option is to use the Regex type. This too will often require custom code. It will likely be slower than the example method.
Performance note. An iterative method that tests characters individually is often the fastest one. Regex has overhead. The downside to using For-loops is that it involves more lines of code.
For Each, For
Summary. This function removes punctuation and is efficient. Some ways to remove punctuation are better than others—and testing for correctness is important.
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This page was last updated on Mar 19, 2022 (rewrite).
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