C# Generics Interview Questions

Introduction

Hello Ninjas! How are you doing? Today's topic of discussion is C# generics interview questions. Before we start the questions, let us understand the C# generics.

Generic refers to the general form, not the specific form. In C#, generic means not tied to a particular data type.

You can define generic classes, interfaces, abstract classes, fields, methods, static methods, properties, events, delegates, and operators using the type parameter and without the specific data type. Let us move ahead to the section of C# generics interview questions.

Top 28 C# Generics Interview Questions

We have divided the C# Generics Interview Questions into different levels - Easy, Medium and Hard. Let us look into each one of them starting in detail. 

1. Why are generics required in C#?

Ans: C# uses generic types to increase code reuse, type safety, and performance. The most common application of generics is the creation of collection classes. The system contains several generic collection classes and (.NET) class libraries.
 

2. Does C# allow for multiple inheritances?

Ans: No, you cannot inherit from more than one class. You can use interfaces or a mix of classes and interfaces.
 

3. Why can't we store null in value types?

Ans: A reference type is stored as a pointer to an object instance. Null refers to a reference that does not point to an example of an object. Value types are stored as the values themselves, with no references. As a result, having a null value type makes no sense—the value type, by definition, contains a value.
 

4. What are the features of generics?

Ans: These are some features of generics:

• It aids in the optimization of code reuse, type safety, and performance.
• Generic interfaces, classes, methods, events, and delegates can all be created by us.
• Reflection can be used to obtain information at run time in a generic data type.
• We can create generic classes restricted to methods on specific data types.
   

5. In C#, what is the difference between safe and unsafe codes?

Ans: In general, safe code does not use pointers to access memory directly. It does not also allocate raw memory. Instead, it generates managed objects. C# provides an unsafe context where you can write code that cannot be verified. A secure and safe code is run by CLR(Common Language Runtime) management; an unsafe code is not run by CLR management.
 

6. What are generic Delegates?

Ans: Delegates are reference types that support maintaining a reference to a method class. Delegates can be assigned methods that have the same signature as them.

• A delegate can define its type parameters. The type argument can be specified in code that references the generic delegate to create a closed constructed type, just like when introducing a generic class or calling a generic method.
   
• Class methods and delegates defined within a generic class can use generic class-type parameters.
   

7. What are generic type parameters?

Ans: Generic type parameters enable you to create classes and methods that postpone specifying many types until the class or method is declared and initialized by client code.

A generic parameter comprises a type parameter and an optional constraint. A type parameter is nothing more than the name of a placeholder type (for example, T, U, V, Key, Value, and so on).
 

8. Why are constraints used?

Ans: Constraints define a type parameter's ability and expectations. Declaring those constraints allows us to use the constraining type's operations and method calls. 

• Suppose the generic class or method performs any operations on the generic members other than simple assignment or calls any methods not supported by the system. Object constraints will be applied to the type parameter. 
   
• Constraints restrict the types of data that can be entered into a table. This ensures that the data in the table is accurate and reliable. 
   
• The action is aborted if there is a conflict between the constraint and the data action. Constraints can be applied at the column or table level.
   

9. What are generic classes?

Ans: Generic classes sum up the operations that are not data type specific. Generic classes are commonly used with collections such as linked lists, hash tables, stacks, queues, trees, etc. Adding and removing items from a collection are performed similarly regardless of the stored data type.

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10. What types should be generalized into type parameters?

Ans: The types you can parameterize, the more flexible and reusable your code becomes. However, oversimplification can result in code that is difficult to read and understand for other developers.
 

11. Is it possible to have a generic interface in C#?

Ans: The 'in' and 'out' keywords for generic type parameters can be used to declare generic variant interfaces. In C#, the ref, in, and out parameters cannot be variant. Variance is also not supported by value types. The out keyword can be used to declare a generic type parameter covariant.
 

12. What is a generic interface?

Ans: A generic interface is fundamentally the same as any other interface. It can be used to declare a variable while associating it with the appropriate class. It is a method return value. It is possible to pass it as an argument. A generic interface is given the same way an interface is given.
 

13. What are generic methods?

Ans: Generic methods define their type parameters. This is similar to mention in a generic type, except that the scope of the type parameter is limited to the method where it is declared. Static and non-static generic methods, as well as generic class constructors, are permitted.
 

14. What are the key differences between C# Generics and C++ templates?

15. When would you use generics in your code C#?

Ans: Use generic types to increase performance, type safety, and code reuse. You can use it to define generic classes, interfaces, abstract classes, fields, methods, static methods, properties, events, delegates, and operators using the type parameter and without the specific data type.
 

16. How do you declare generics in C#?

Ans: An angle-bracketed type parameter is specified after the type name to declare a generic type.e.g. TypeName<A> where A is a type parameter.
 

17. Why are multiple inheritances not possible in C#?

Ans: The C# compiler does not support multiple inheritances because it causes ambiguity in methods from different base classes. In this case. Diamond cause two types of shape problems If two classes, B and C, are inherited from A, and class D is inherited from both B and C.
 

18. What is polymorphism in C#?

Ans: In C#, polymorphism refers to an object's capacity to offer a distinctive interface for several method implementations.
 

19. What is the use of the 'using' statement in C#?

Ans: The "using" block is used to acquire a resource, use it, and then automatically discard it after the block's execution is complete.
 

20. What are sealed classes in C#?

Ans: When in C#, we don't want a class to be inherited; we build sealed classes. A sealed modifier prevents derivation from a class. A compile-time error happens if we forcefully define a sealed class as a base class.

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21. What makes the direct cast and ctype different from one another?

Ans: The type of object that needs the run-time type to match the specified type in DirectCast is converted using DirectCast. When there is a defined conversion between an expression and a type, Ctype is used.
 

22. What are C# I/O classes? Define the commonly used I/O classes.

Ans: Classes for creating, deleting, opening, closing, and other file-related actions can be found in the System.IO namespace of the C# programming language.
 

23. What is a generic programming language?

Ans: A computer programming method known as generic programming involves writing algorithms in terms of later-specified types that are then instantiated as necessary for particular types supplied as inputs.
 

24. What are the various Thread states in C#?

Ans: The following are the different states of a thread in C#:

• Aborted: The thread has died but has not been terminated.
• Running: This indicates that the thread is active.
• Stopped: This means that the thread has completed the implementation.
• Suspended: The thread has been put on hold.
   

25. Why can you have only one static constructor?

Ans: To define multiple constructors for any given class, constructors must be overloaded. Parameterized constructors that can accept outside parameters must be defined for this. Static constructors can only be called through CLR, which cannot pass parameters to parameterized constructors.
 

26. List down the different IDEs provided by Microsoft for C# Development.

Ans: The IDE'S provided by Microsoft for C# Development:

• Visual Studio Express (VSE)
• Visual Studio (VS)
• MonoDevelop
• browxy
   

27. Illustrate Namespaces in C#?

Ans: The namespace is a keyword that specifies a scope that contains a collection of related objects. A namespace can be used to organize code elements and to create globally unique types.

Large coding projects are structured using namespaces. Nesting is the process of using one namespace inside another.
 

28. Define a Jagged Array in C#?

Ans: An "array of arrays" is the term used to describe a Jagged array. It is an array whose elements are arrays; each element's size and dimensions can vary. Each array index might have a different length.