Table of Contents

Trimming

ValueStringBuilder offers a Trim family that mirrors string.Trim/TrimStart/TrimEnd, plus prefix/suffix removal that string doesn't have. All of them mutate the builder in place - no new buffer is allocated, only the internal position is adjusted (and the remaining characters shifted left if the start changed).

The whitespace-based overloads (Trim(), TrimStart(), TrimEnd()) are vectorized with SearchValues<char>, so they are considerably faster and lower-allocating than trimming a System.Text.StringBuilder - see the comparison article for numbers.

Trimming whitespace

using var stringBuilder = new ValueStringBuilder("   Hello World   ");

stringBuilder.Trim();

Console.WriteLine(stringBuilder.ToString()); // "Hello World"

TrimStart() and TrimEnd() work the same way but only remove leading or trailing whitespace respectively:

using var stringBuilder = new ValueStringBuilder("   Hello World   ");

stringBuilder.TrimStart();
Console.WriteLine(stringBuilder.ToString()); // "Hello World   "

stringBuilder.TrimEnd();
Console.WriteLine(stringBuilder.ToString()); // "Hello World"

Trimming a specific character

Each method also has an overload that removes a specific character instead of whitespace:

using var stringBuilder = new ValueStringBuilder("xxHello Worldxx");

stringBuilder.Trim('x');

Console.WriteLine(stringBuilder.ToString()); // "Hello World"

This is useful for cleaning up padding characters, for example the ones produced by AppendPadLeft/AppendPadRight:

using var stringBuilder = new ValueStringBuilder();
stringBuilder.AppendPadLeft("42", 10, '0');
Console.WriteLine(stringBuilder.ToString()); // "0000000042"

stringBuilder.TrimStart('0');
Console.WriteLine(stringBuilder.ToString()); // "42"

Trimming a prefix or suffix

TrimPrefix and TrimSuffix remove a whole sequence of characters (not just a single one) if the builder starts or ends with it. Unlike the other Trim overloads they take a StringComparison, so you can opt into a case-insensitive comparison:

using var stringBuilder = new ValueStringBuilder("https://example.com/");

stringBuilder.TrimPrefix("https://");
stringBuilder.TrimSuffix("/");

Console.WriteLine(stringBuilder.ToString()); // "example.com"

using var stringBuilder = new ValueStringBuilder("HELLO.txt");

stringBuilder.TrimSuffix(".TXT", StringComparison.OrdinalIgnoreCase);

Console.WriteLine(stringBuilder.ToString()); // "HELLO"

If the builder doesn't start (or end) with the given value, TrimPrefix/TrimSuffix are a no-op.

Combining Trim with a stack-allocated buffer

Because none of the Trim methods allocate, they combine well with a stackalloc-backed builder for fully allocation-free processing of short-lived strings:

Span<char> buffer = stackalloc char[64];
var stringBuilder = new ValueStringBuilder(buffer);

stringBuilder.Append("   raw input   ");
stringBuilder.Trim();

ReadOnlySpan<char> result = stringBuilder.AsSpan(); // no allocation at all
Edit this page