Introducing C#11: UTF-8 String Literals

Introduction

.NET encodes strings with UTF-16 encoding. However in the world of the web, the encoding used is UTF-8 so when a developer tries to create strings in UTF-8 it becomes tedious. C# 11 fixes this by making it easier to create UTF-8 strings. In this post I will show you how.

An easier way to create UTF-8 strings

Usually encoding a string into an UTF-8 byte representation would be made as follow:

However, it leads to mutable array of bytes and it’s not performant because the encoding is made at the runtime. C# 11 simplifies it with a lighter syntax (u8 suffix), and the UTF-8 type is enforced at the compile time which makes the encoding process more performant, bonus it’s represented by an immutable ReadOnlySpan<byte> type:

If you still want to get an array of byte you can do the following:

Note that the ReadOnlySpan<byte> or byte[] types are enforced at compile time BUT UTF-8 strings aren’t compile time constants, so it means they can’t be used as default parameters in functions and will lead to a comilation error:

Error CS1736 Default parameter value for ‘message’ must be a compile-time constant.

Example:

Conclusion

Keep in mind that the usage of UTF-8 Strings literals would be restricted to web scenarios, so you won’t use this feature that often. Anyways, if you have to use UTF-8 Strings Literals feature, I hope this post would help you