Is There a Functional Difference Between Lambda Notation and the Delegate Keyword in C#?

Delegate Invocation: Lambda Notation vs. Delegate Keyword

In C#, lambda expressions and delegate keywords offer alternative syntax for creating anonymous methods. Once compiled, is there any discernible difference between the following two notations?

delegate { x = 0; }

and

() => { x = 0; }

Answer: No Functional Difference

At the binary level, both lambda notation and the delegate keyword produce equivalent anonymous delegates. They can be invoked interchangeably and exhibit the same runtime behavior.

Additional Considerations:

• When assigning a lambda to a delegate type (e.g., Func or Action), an anonymous delegate is directly created.
• Assigning a lambda to an Expression type, on the other hand, yields an expression tree instead of an anonymous delegate. This expression tree can subsequently be compiled to create an anonymous delegate.

Expression Trees and LINQ:

In the context of LINQ, understanding expression trees is crucial. LINQ operations in-memory (e.g., using Enumerable) employ delegates, while LINQ operations with external data sources (e.g., SQL) utilize expression trees.

For further insights and resources on expression trees, refer to the following links:

• [System.Linq.Expression.Expression(TDelegate)](https://docs.microsoft.com/en-us/dotnet/api/system.linq.expressions.expression)
• [Linq in-memory with delegates (System.Func) vs. Linq to SQL with expressions (System.Linq.Queryable)](https://stackoverflow.com/questions/9289889/linq-in-memory-with-delegates-system-func-vs-linq-to-sql-with-expressions-syst)
• [An Explanation from ScottGu](https://weblogs.asp.net/scottgu/a-look-ahead-at-linq)

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