C# method declarations using the lambda operator [

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What is the => assignment in C# in a property signature (6 answers)

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While researching C# operator overloading, I stumbled across this block of code on the MSDN web site:

public static Complex operator +(Complex c1, Complex c2) =>
    new Complex(c1.real + c2.real, c1.imaginary + c2.imaginary);

// Override ToString() to display a complex number 
// in the traditional format:
public override string ToString() => $"{this.real} + {this.imaginary}";

This is a really useful way of defining simple methods in certain circumstances, but I don't recall ever seeing it described anywhere. I tried searching the C# 5.0 language specification for a description of this method declaration syntax, but could find nothing. I also found nothing in my web searches.

Two questions:

1. In which version of C# did this method declaration syntax become available?
2. Where in the language specification is this syntax described?

Answer 1

It was added in C# 6, you can read about it on the official Github of the new compiler here.