How Can I Escape and Unescape Unicode Strings in C# to Maintain ASCII Compatibility?

Handling Unicode Strings in ASCII Environments with C#

Maintaining Unicode characters within ASCII-encoded strings is crucial in specific situations. This article provides a method to convert Unicode strings into escaped ASCII equivalents and back, overcoming C#'s Encoding limitations (e.g., converting π to "?")

The Encoding Challenge

C#'s built-in Encoding class treats characters beyond the ASCII range (0-127) as invalid, replacing them with "?". This is problematic when preserving Unicode characters in ASCII contexts is necessary.

Solution: Escaping and Unescaping Unicode Characters

Our solution replaces non-ASCII characters with their escaped ASCII representations using the uXXXX format. u signifies a Unicode character, followed by its hexadecimal code point. This ensures the original Unicode characters are preserved when encoded in ASCII.

Encoding Non-ASCII Characters

The encoding process iterates through the input string. If a character exceeds the ASCII range, its escaped representation is appended to a StringBuilder.

Decoding Escaped Unicode Characters

The decoding process utilizes regular expressions. Regex.Replace identifies escaped Unicode sequences (uXXXX) and converts them back to their corresponding Unicode characters.

Practical Example

The following C# code demonstrates the encoding and decoding process:

<code class="language-csharp">string unicodeString = "This function contains a unicode character pi (\u03a0)";

Console.WriteLine(unicodeString);

string encoded = EncodeNonAsciiCharacters(unicodeString);
Console.WriteLine(encoded);

string decoded = DecodeEncodedNonAsciiCharacters(encoded);
Console.WriteLine(decoded);</code>

The output will be:

<code>This function contains a unicode character pi (π)
This function contains a unicode character pi (\u03a0)
This function contains a unicode character pi (π)</code>

This showcases the effective conversion between Unicode strings and their escaped ASCII versions, preserving Unicode characters in ASCII environments.

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