Word Boundaries Regex

\b

This is the second time this week where I have had to ask myself "how did I not know about this?"

There is a regex character to identify word boundaries: \b This is a zero length match, similar to the caret and dollar sign. It finds the boundaries between words, allowing you to search for a whole word match.

Below is a sample extension method that uses this to replace words in a string.

Implementation

public static class StringExtensions

{

    private static readonly Regex WordRegex = new Regex(@"\b\w+\b", RegexOptions.Compiled);

    public static string ReplaceWords(

        this string input,

        string find,

        string replace,

        StringComparison comparison = StringComparison.InvariantCulture)

    {

        return WordRegex.Replace(input, m => m.Value.Equals(find, comparison)

            ? replace

            : m.Value);

    }

}

Unit Test

public class StringExtensionsTests

{

    [Fact]

    public void ReplaceWords()

    {

        Assert.Equal(

            "This island can has beautiful",

            "This island is beautiful".ReplaceWords("is", "can has"));

        Assert.Equal(

            "This island are beautiful",

            "This island is beautiful".ReplaceWords(

                "IS", 

                "are", 

                StringComparison.InvariantCultureIgnoreCase));

    }

}

Enjoy,
Tom