C# - what does the unary ^ do?

Question

I have checked out some code and I got an error ('invalid expression term "^"' to be exact) in the line

// choices is a regular array
return choices[^1];

I have never seen a unary caret operator (I am only aware of the XOR operator, but that one obviously takes two operands). Does this operator exist and if so, what does it do?

Note: The site https://www.tutorialsteacher.com/csharp/csharp-operators mentions a unary caret operator in the precedence table but it does not explain what it does.

Answer 1

Unary ^ is the "index from end" operator, introduced in C# 8.0. choices[^1] is equivalent to choices[choices.Length - 1].

See the official documentation for additional details.