C# is a general-purpose programming language and it was developed by Microsoft with the .Net framework. It is based on an object-oriented concept that makes it a modern programming language and C# professionals are being hired by top companies.
Here we have presented popular and frequently asked C# Interview Questions and Answers to help you clear the technical rounds easily.
- Explain C#
C Sharp is created by Microsoft that runs on the .Net Framework and it is based on OOPs concepts that make it a modern programming language. C# Programming language is easy to learn by people who are proficient in C, C++, or Java. C# is a simple but modern programming language and this is used for creating software components.
- Define CLR
CLR stands for Common Language Runtime is the basic and virtual machine component of the .Net framework. .Net has CLR as the runtime environment for executing the codes to make the development process easier by offering various services like remoting, type-safety, robustness, thread management, memory management, and so on.
CLR is responsible for managing the execution of .Net programs irrespective of any .Net and it helps in the code management. If the code that targets the runtime is known as the managed code and if the code that doesn’t target the runtime is known as unmanaged code.
- Define indexers in .Net
Indexers are smart arrays in C# that allow the instances of a class to be indexed in the same manner as an array. When the user defines an indexer for a class that behaves like a virtual array and it can be accessed the instance of this class using the array access operator ().
element_type this [int index]
get //the get accessor
//return the value defined by the index
set //the set accessor
//set the value defined by the index
- Define the JIT compiler process
JIT is the Just In Time compiler that is part of CLR (Common Language Runtime) and it is responsible for managing the execution of .Net programs. This is a language-specific compiler that converts source code into intermediate language and then into machine code.
It requires less memory usage, page defaults will be reduced, and code optimization based on statistical analysis.
- Explain Garbage Collection in C#
Garbage Collection of .Net Framework is used for automatic memory management. Whenever a class object is created at runtime, the memory space will be allocated to it in the heap memory. If the actions have been completed with the object, the allocated space will be wasted and unused.
There comes the garbage collection that is used for managing the unused space by releasing the memory. It will work on the managed heap and it has an engine that is known as Optimization Engine.
- List the types of classes in C#
The various types of classes in C# are abstract class, partial class, sealed class, and static class.
- Differentiate struct and class in C#
A class is a user-defined prototype for which objects will be created. It combines fields and methods into a single unit. A struct, on the other hand, is a collection of variables of different data types under a single unit.
- Explain Enum in C#
Enum also known as Enumeration is a data type used to assign the names or string values to integral constants that make a program easy to read and maintain.
The main purpose of using Enum is to define the user-defined data types that are known as Enumerated data types. It will be declared using the Enum keyword inside a namespace, structure, or class.
- Explain boxing and unboxing in C#
Boxing and unboxing are used to allow a unified view of the type system in which a value of any type is treated as an object.
Boxing is the process of converting a value type like char or int into a reference type object. It is an implicit conversion process where the object type is used. The value type will be stored in Stack and the reference type will be stored in Heap.
Unboxing is the process of converting back the reference type into the value type and it is an explicit conversion process.
- Explain properties in C#
Properties are the unique type of class members that offers a flexible mechanism to read, write, or compute the value of a private field.
When they are used as public data members, they will be called accessors. It enables data to be accessed easily to help promote the flexibility and safety of methods.
Properties empower encapsulation and hiding of information and they use pre-defined methods that get and set methods to help to access and modify the properties.
- Explain partial classes in C#
The partial class is a unique feature in C# that provides a special ability for implementing the functionality of a single class into multiple files and all the files will be combined into a single class file when the application is compiled.
The partial class is created using a partial keyword and the following is the syntax to create a partial class
public partial class_name
//codes to execute
- Differentiate late binding and early binding in C#
C# compiler performs the binding with the help of the .Net framework when the object is assigned to an object variable of a specific type. It has two different types of bindings as follows
- Early binding
- Late binding
Early binding is fast and easy to code as it recognizes and checks the methods and properties during the compile time. In this early binding, the compiler knows about what kind of object it is and what are the methods or properties it holds earlier as the objects are static.
The limitation of early binding is it increases the number of runtime errors.
Late binding is performed by using virtual methods and the compiler doesn’t know about what kind of object it is or what the methods it holds as the objects are dynamic. Late binding performs slower as it needs lookups at runtime.
- Define Reflection in C#
Reflection is the process of identifying the metadata of types, fields, and methods in the code.
It enables the user to obtain data of the loaded assemblies, and the elements within them like methods, value types, and classes.
- Differentiate constant and read-only in C#
A constant is a keyword used to declare constant fields and constant local. The value of the constant field is the same throughout the program. Once the constant field is assigned the value of this field, it will not be changed.
The read-only keyword is used to define a read-only variable and it shows that it can assign the variable only when we declare a variable or a constructor of the same class where it is declared.
- Explain Jagged Array
A jagged array is an array of arrays that member arrays can be of various sizes. The length of every array index will be varied and the elements of the jagged array are reference types and initialized to null by default.
A jagged array will be mixed with multidimensional arrays that the number of rows will be fixed at the declaration time but can be differed in the number of columns.
- Explain delegates in C#
Delegates in C# are objects that refer to a method or it is a reference type variable that holds a reference to the methods.
They are the same as the function pointer in C or C++ and it provides a way that shows which method to be called when an event is triggered.
It is a type that defines references to methods with a particular parameter list for the return type and calls the method in a program for execution when it is required.
- Explain sealed classes in C# with syntax
Sealed classes are implemented in the C# program to restrict users from inheriting the class and a class can be sealed using the sealed keyword.
It tells the compiler that the class is sealed and it can’t be extended. No class will be derived from a sealed class. The following syntax is for the sealed class.
sealed class class_name
A method is sealed and the method can’t be overridden. It can be sealed in the classes where they have been inherited. It has to be declared as a virtual class in its base class if you want to declare a method as sealed.
- Explain Generics in C#
Generic is a class that enables the user to define classes and methods with a placeholder. It will be added to version 2.0 of the C# language. The fundamental idea of generic is to allow the type to be a parameter to methods, interfaces, or classes.
- Explain hash table class in C#
The hash table class defines a collection of key/value pairs that are structured based on the hash code of the key. It comes under the System.
Collection namespace. The hash table class offers various types of methods used to perform various types of operations on the hash tables.
The hash table keys are used to access the elements in the collection. We can increase the maximum ability to 2 billion elements on a 64-bit system for very large hash table objects.
- Define LINQ in C#
LINQ stands for Language Integrated Query which is introduced in .Net 3.5 and Visual Studio 2008. LINQ provides the ability to .Net languages like C# and VB.Net to create queries to extract data from the data source.
If a program gets information from the student records or accesses employee records, the data is stored in a separate database from the application and it is important to learn query languages like SQL or XML and it can’t create a query using C# language.
To resolve this issue, LINQ is implemented for generating queries irrespective of the data source
- What are the commonly used types of exceptions?
An exception is an error that happens at runtime and using the C# exception handling subsystem during a structured and controlled manner that handles runtime errors.
The main aim of exception handling is to automate the error handling code as it defines standard exceptions for common program errors like divide-by-zero or index-out-of-range.
- ArrayTypeMismatchException comes when the Type of value is stored incompatible with the type of the array.
- DivideByZeroException comes when the user tries to separate an integer value by zero.
- IndexOutOfRangeException comes when an array index is out-of-bounds if an exception occurred.
- InvalidCastException is an invalid runtime cast
- OutOfMemoryException comes when an insufficient free memory exists to continue program execution.
- OverFlowException is an arithmetic overflow that occurred.
- NullReferenceException is a try that was made to operate on a null reference as a reference doesn’t refer to an object.
- Explain Singleton design pattern in C#
Singleton design pattern is a common design pattern for a class that has one instance in the program that provides global access to it.
It is a class that allows only one instance of itself to be made and gives simple access to the instance. There are various approaches and methods to perform a singleton design in C# and they are as follows
- Private and parameterizes single constructor
- Sealed classes
- Static variable to hold a reference to the single made instance
- Public and static method of getting the reference to the made instance
- Explain the ways to implement a singleton design pattern in C#
Users can implement a singleton design pattern in C# in the following ways
- No thread-safe singleton
- Thread-safety singleton
- Thread-safety singleton using Double-Check locking
- Thread-safe without a lock
- Using .Net 4’s lazy <T> type.
- Define Tuple in C#
Tuple means a data structure that contains multiple parts and it gives the easiest way to define a data set. It has multiple values that may not be related to each other. It is introduced in .Net framework 4.0 and it adds elements from 1 to 8.
Tuples are used to create a data structure that consists of objects with their properties and it doesn’t require a separate type for that.
- Describe Events in C#
An event is a notification to notify when the action has occurred and delegates and events are relatively the same as an event is developed on a delegate. They expand the set of programming tasks where C# can be implemented. It is the main feature of C# to automate notification.
Events are members of a class and they will be declared using the event keyword. It will be applied as follows
event event-delegate event-name;
The ‘event-delegate’ is the name that the delegates used to support the event and the ‘event-name’ is the name for the particular event object that is being declared in the C# program.
C# is the in-demand skill that brings tremendous opportunities for freshers and working professionals to develop applications for various purposes.
It has numerous features and benefits that help developers to build applications faster and more efficiently. We hope these C# Interview Questions and Answers help you ace the technical rounds easily in top companies.