What Does => (Lambda Operator) Mean in C#?

What Does => (Lambda Operator) Mean in C#?

If you’ve used C++ before, the => operator in C# might feel unfamiliar and confusing at first. However, this operator is used in many different ways in C#, and it plays a key role in writing cleaner and more readable code.

In C#, the => symbol is called the lambda operator. It's most commonly used in lambda expressions, which are a concise way to write small, inline functions.

In this post, we’ll walk through how the => operator works and where it's commonly used, with simple examples.

Common Uses of the => Operator

The => operator appears often in lambda expressions and delegate declarations.

Func<int, int> square = x => x * x;
Action greet = () => Console.WriteLine("Hello!");

The first line defines a lambda that takes x and returns x * x.
The second line defines an Action that prints "Hello!" with no parameters.

Comparing to Traditional Code

The => operator can also be used in method definitions. Here’s a comparison between the regular syntax and the simplified one using =>.

// Traditional method
class MathUtil
{
    public int Square(int x)
    {
        return x * x;
    }
}

// Expression-bodied method
class MathUtil
{
    public int Square(int x) => x * x;
}

For simple logic, using => makes the code much more concise.

What the => Operator Really Means

The => operator is essentially a shortcut for returning a value without using return and braces { }.

public int Add(int x, int y)
{
    return x + y;
}

can be written like this:

public int Add(int x, int y) => x + y;

It's a clean way to write short methods.

Using => in Property Accessors

The => operator can also be used with property get and set accessors, especially when the logic is simple.

public override string Text
{
    get => base.Text;
    set => base.Text = value;
}

This code means:

  • The get accessor returns base.Text.
  • The set accessor assigns the value to base.Text.

This reduces unnecessary code and improves readability.

You might also come across code like this:

public string Name => _name;

It may look like the get keyword is missing, but it’s not.
This is actually an expression-bodied read-only property, and C# internally treats it as:

public string Name
{
    get { return _name; }
}

So get is not really omitted—it’s just implicitly handled by the compiler.

Be Careful With This

// This will cause a compile error
public string Name => _name;
set => _name = value;

This code results in a syntax error.
Why? Because the first line already declares the entire property using an expression body.
C# sees it as a complete, get-only property and does not allow adding set afterward like that.

The Right Way

If you want to use => with both get and set, you must define both inside a property block:

public string Name
{
    get => _name;
    set => _name = value;
}

This syntax is supported from C# 7.0 onward.

Summary

  • The => operator is a shorthand for return and { }.
  • It’s used in lambdas, methods, and properties.
  • A get-only property can be fully written using =>.
  • The set accessor can use => too, but only inside a property block.
  • You cannot use => for the entire property and then add a set afterward.

At first, the syntax may feel unfamiliar, but once you get used to it, you’ll be able to write cleaner and more efficient C# code.

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