How Can I Perform Whole-Word String Replacement in C# and VB.NET?

Implementing Whole-Word String Replacement

In certain cases, when performing string replacement using the Replace() function, it might be undesirable to replace partial word matches and only target complete words. This article delves into a method to address this requirement by leveraging regular expressions.

Approach Using Regular Expressions

A regular expression can be employed to ensure that only whole words are matched and replaced. Here's an example in C#:

string input = "test, and test but not testing.  But yes to test";
string pattern = @"\btest\b";
string replace = "text";
string result = Regex.Replace(input, pattern, replace);
Console.WriteLine(result);

The pattern "btestb" is the key here. The b metacharacter signifies word boundaries, meaning it will match only where "test" appears as a complete word, not within longer words like "testing."

Case-Insensitive Matching

If case-insensitive matching is required, the RegexOptions.IgnoreCase flag can be used:

Regex.Replace(input, pattern, replace, RegexOptions.IgnoreCase);

VB.NET Equivalent

For use in VB.NET, the following code would achieve the same result:

Dim input = "test, and test but not testing.  But yes to test"
Dim pattern As String = "\btest\b"
Dim replace As String = "text"
Dim result As String = Regex.Replace(input, pattern, replace)
Console.WriteLine(result)

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