Part 1 We use a metacharacter to match at the start of a string. The next metacharacter then matches whitespace.
Part 2 We use the dollar sign at the end to match the end of a string. This trims the end of the string.
using System;
using System.Text.RegularExpressions;
string source = " Some text ";
// Part 1: use the ^ to match at the start.// ... 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+", "");
// Part 2: trim with a $ on the end.// ... This requires that we match at the end.
source = Regex.Replace(source, @"\s+$", "");
Console.WriteLine($"[{source}]");[Some text]
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.
using System;
using System.Text.RegularExpressions;
// Use both regular expressions at once.
string source = " cat\n";
source = Regex.Replace(source, @"^\s+|\s+$", "");
Console.WriteLine($"[{source}]");[cat]
If you need Trim with different requirements than the built-in methods, the Regex methods will be easier. If it is reasonable to use the built-in Trim, this is preferable.
With Regex in the C# language we can trim the starts and ends of strings. For many tasks, such as processing data in the background, Regex is ideal.
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This page was last updated on Mar 5, 2025 (new example).