Regex Trim ExampleRemove start and end whitespace from strings with Regex.Replace. Trim strings with patterns.
This page was last reviewed on Oct 28, 2021.
Regex, trim. Regex can be used to trim whitespace. Trimming a string removes whitespace and leaves only the important contents.
Shows a regex
C# method info. Several methods are available, each with pluses and minuses. We trim strings using Regex in the C# programming language.
Example. One problem we might encounter is multiple-line strings. With Regex, you must indicate how you want the engine to treat newlines (\n).
Note The two options we use are RegexOptions.Multiline and RegexOptions.Singleline.
Note 2 My requirements were to trim the beginning and ending whitespace from a medium size (maybe several kilobytes) string.
Shows a regex
using System; using System.Text.RegularExpressions; class Program { static void Main() { // // Example string // string source = " Some text "; // // Use the ^ to always match at the start of the string. // Then, look through all WHITESPACE characters with \s // Use + to look through more than 1 characters // Then replace with an empty string. // source = Regex.Replace(source, @"^\s+", ""); // // The same as above, but with a $ on the end. // This requires that we match at the end. // source = Regex.Replace(source, @"\s+$", ""); Console.Write("["); Console.Write(source); Console.WriteLine("]"); } }
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Combined Regex. Here we look at another way you can trim strings using Regex. We combine the 2 regular expressions into one, and then use a single Regex Replace call.
Start: ^\s+ End: \s+$ Both: ^\s+|\s+$
Compiled. Compiled regexes do make a substantial performance improvement. My quick tests showed that for using two compiled regexes 1,000 times each was about 47% faster than not compiling them.
Discussion. If you need Trim with different requirements than the built-in methods, the Regex methods will be easier. If it is at all reasonable for you to use the built-in Trim, do so.
String Trim
String TrimEnd, TrimStart
Summary. We looked at some methods of trimming the starts and ends of strings using Regex in the C# language. For many tasks, such as processing data in the background, Regex is ideal.
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Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Oct 28, 2021 (image).
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