Which delegates support covariance and Contravariance in C#?

Generic delegates with variant type parameters. The Func generic delegates, such as Func, have covariant return types and contravariant parameter types. The Action generic delegates, such as Action, have contravariant parameter types.

What is covariance and Contravariance in C# and how is it used?

In C#, covariance and contravariance enable implicit reference conversion for array types, delegate types, and generic type arguments. Covariance preserves assignment compatibility and contravariance reverses it. string str = “test”; // An object of a more derived type is assigned to an object of a less derived type.

How do you declare a generic interface as contravariant?

You can declare a generic type parameter contravariant by using the in keyword. The contravariant type can be used only as a type of method arguments and not as a return type of interface methods. The contravariant type can also be used for generic constraints.

Why is covariance and Contravariance important?

This is mainly useful when using already defined standard interfaces. Covariance means that you can use IEnumerable in place where IEnumerable is expected. Contravariance allows you to pass IComparable as an argument of a method taking IComparable . So far, so good.

What is the difference between covariance and Contravariance?

A device which can compare two Animals can also compare two Tigers, but a device which can compare two Tigers cannot necessarily compare any two Animals. So that’s the difference between covariance and contravariance in C# 4. Covariance preserves the direction of assignability. Contravariance reverses it.

What is Generics in C #? What are the benefits of generics?

Features of Generics: It helps you to maximize code reuse, type safety, and performance. You can create generic collection classes. You can create your own generic interfaces, classes, methods, events, and delegates. You may create generic classes constrained to enable access to methods on particular data types.

What is Generics in C#? What are the benefits of generics?

What is delegate C#?

A delegate is a type that represents references to methods with a particular parameter list and return type. When you instantiate a delegate, you can associate its instance with any method with a compatible signature and return type. In other words, a method must have the same return type as the delegate.

What is covariance in C#?

Covariance in C# Covariance enables you to pass a derived type where a base type is expected. Co-variance is like variance of the same kind. The base class and other derived classes are considered to be the same kind of class that adds extra functionalities to the base type.

Why do we need generics C#?

Generics overview Use generic types to maximize code reuse, type safety, and performance. The most common use of generics is to create collection classes. The . You can create your own generic interfaces, classes, methods, events, and delegates.

What all are the advantages and disadvantages of generics in C#?

Advantages and disadvantages of generics

• Type safety.
• Less code and code is more easily reused.
• Better performance.
• Generic delegates enable type-safe callbacks without the need to create multiple delegate classes.
• Generics streamline dynamically generated code.

Why do we need generic collection in C#?

Generics in C# is its most powerful feature. It allows you to define the type-safe data structures. Generic types perform better than normal system types because they reduce the need for boxing, unboxing, and type casting the variables or objects. Parameter types are specified in generic class creation.