19. What is the purpose of the "var" keyword in C#?
- To specify the type of a variable.
- To indicate that a variable cannot be changed once it has been assigned a value.
- To indicate that a variable should be initialized with a default value.
- To allow developers to declare variables without specifying their types explicitly.
20. What is the purpose of an event in C#?
- To define a new class.
- To encapsulate a method call and its parameters.
- To provide a mechanism for one object to notify other objects when an event occurs.
- To define a block of code that can be called from multiple places in a program.
21. What is a lambda expression in C#?
- A way to define a new class.
- A way to define a new variable.
- A way to define an anonymous method.
- A way to define a property.
22. What is an expression tree in C#?
- A data structure that represents a lambda expression as a tree of expression nodes.
- A mechanism for passing a block of code as a parameter to a method.
- A way to define a new class.
- A way to define a new variable.
23. What is the difference between var and dynamic in C#?
- var is used for static type inference, while dynamic is used for dynamic type binding.
- var is used for dynamic type binding, while dynamic is used for static type inference.
- There is no difference between var and dynamic in C#.
- var and dynamic are both used for static type inference.
24. What is an expression tree in C#?
- A tree data structure that represents a lambda expression.
- A tree data structure that represents a list of expressions.
- A tree data structure that represents a sequence of executable instructions.
- A tree data structure that represents a data object with multiple properties.