Here are some commonly asked .NET interview questions and their answers:
What is .NET framework?
The .NET framework is a software development platform developed by Microsoft that provides a comprehensive programming model for building, deploying, and running modern applications and services.
What is the difference between .NET Framework and .NET Core?
The .NET Framework is a mature and full-featured framework that has been around for over a decade and is optimized for Windows. It provides support for a wide range of technologies and scenarios, including desktop applications, web services, and enterprise-level applications. .NET Core is a relatively new, cross-platform, and open-source version of the .NET framework that is optimized for modern cloud-based and container-based deployment scenarios.
What is the Common Language Runtime (CLR)?
The Common Language Runtime (CLR) is the runtime environment of the .NET framework. It provides the foundation for executing .NET code and managing memory, resources, and security. The CLR also provides services such as just-in-time (JIT) compilation, garbage collection, and exception handling.
What is the role of the .NET Base Class Library (BCL)?
The .NET Base Class Library (BCL) is a comprehensive and extensive library of classes, interfaces, and value types that provide common functionality for .NET applications and services. The BCL includes classes for file I/O, data access, security, network communication, and many other common tasks and scenarios.
What is an assembly in .NET?
An assembly is a self-contained unit of deployment in .NET. It contains compiled code, resources, and metadata that describe the types, version information, and security requirements of the code. Assemblies can be executed, deployed, and versioned independently, making them a fundamental building block for .NET applications and services.
What is a namespace in .NET?
A namespace is a logical grouping of types and members in .NET. Namespaces are used to organize and categorize the types in an application or library and to avoid naming conflicts between types with the same name.
What is the role of the Global Assembly Cache (GAC)?
The Global Assembly Cache (GAC) is a centralized repository of .NET assemblies that are shared by multiple applications on a machine. The GAC provides a common location for sharing assemblies and ensures that multiple applications can use the same version of a shared assembly without interfering with each other.
What is an Interface in .NET?
An interface in .NET is a blueprint of a class that defines a set of methods, properties, events, and indexers. Interfaces allow for creating loosely coupled and extensible applications by defining contracts that specify the behavior that a class must implement.
What is inheritance in .NET?
Inheritance is a key feature of object-oriented programming that allows a derived class to inherit members (fields, methods, properties, events, and so on) from a base class. Inheritance enables code reuse, promotes encapsulation, and supports polymorphism.
What is a delegate in .NET?
A delegate in .NET is a type that defines a reference to a method. Delegates are used to pass methods as arguments to other methods and to dynamically invoke methods. Delegates are often used in event-driven programming to allow methods to be subscribed to and unsubscribed from events.
What is an object in .NET?
An object in .NET is an instance of a class. Objects are the fundamental building blocks of object-oriented programming and represent real-world entities such as people, places, and things.
What is the difference between value type and reference type in .NET?
Value types in .NET directly contain their data and are stored on the stack. When a value type is assigned to a variable, a copy of the value is created. Reference types, on the other hand, store a reference to the data and not the data itself. Reference types are stored on the heap and when a reference type is assigned to a variable, a reference to the same object is created.
What is the difference between an Abstract Class and an Interface in .NET?
An abstract class in .NET is a base class that provides a common implementation for its derived classes. An abstract class can contain both abstract and concrete methods. An interface, on the other hand, defines only the signatures of its methods, properties, and events, and not their implementation. An interface can be implemented by multiple classes, allowing for multiple inheritance in .NET.
What is the difference between System.String and System.StringBuilder in .NET?
System.String is an immutable string type in .NET. When a string is modified, a new string object is created to reflect the change. System.StringBuilder is a mutable string type that allows for the efficient modification of strings by avoiding the creation of new objects for each modification.
What is the difference between a stack and a queue in .NET?
A stack in .NET is a last-in, first-out (LIFO) data structure, where the most recently added element is the first to be removed. A queue, on the other hand, is a first-in, first-out (FIFO) data structure, where the first element added is the first to be removed.
What is a LINQ query in .NET?
LINQ (Language-Integrated Query) is a feature of .NET that provides a unified and consistent way to query data from a variety of sources, including collections, arrays, databases, and XML. LINQ allows developers to write SQL-like queries in their code using LINQ syntax, providing a more concise and readable way to retrieve and manipulate data.
What is a NullReferenceException in .NET?
A NullReferenceException in .NET is an exception that is thrown when you try to access a member of a null object reference. This exception indicates that you have attempted to access an object reference that is null, rather than pointing to an instance of an object.
What is the difference between a Hashtable and a Dictionary in .NET?
A Hashtable in .NET is a data structure that implements a key/value pair and is based on the hash code of its keys. A Dictionary in .NET is a generic implementation of a key/value pair that is based on a hash table, providing a more efficient and type-safe alternative to the Hashtable.
What is the difference between a Debug build and a Release build in .NET?
A Debug build in .NET is a version of the code that is compiled for debugging purposes and includes symbols and debugging information. A Release build, on the other hand, is a version of the code that is optimized for performance and is intended for deployment to production environments.
What is the role of the garbage collector in .NET?
The garbage collector in .NET is responsible for managing the allocation and release of memory for objects. It automatically frees memory for objects that are no longer in use and prevents memory leaks, making it easier for developers to write memory-safe and efficient code.
What is the difference between dynamic and var in .NET?
The "dynamic" keyword in .NET is used to declare a variable as dynamic, meaning that its type is not known at compile time and is instead determined at runtime. The "var" keyword, on the other hand, is used to declare a variable as a implicitly typed local variable, meaning that its type is inferred from the expression used to initialize it.
What is a delegate in .NET?
A delegate in .NET is a type that represents references to methods with a particular signature. Delegates can be used to pass methods as arguments to other methods, making it possible to implement callbacks and events in .NET.
What is a class in .NET?
A class in .NET is a blueprint for creating objects that defines a set of properties and methods. Classes provide a way to encapsulate data and behavior into a single unit, making it possible to reuse and extend functionality in your code.
What is inheritance in .NET?
Inheritance in .NET is a feature of object-oriented programming that allows you to define a new class based on an existing class, inheriting its properties and methods. Inheritance enables you to create new classes that are specialized versions of existing classes, making it easier to reuse and extend functionality in your code.
What is an exception in .NET?
An exception in .NET is an abnormal event that occurs during the execution of a program that disrupts the normal flow of instructions. Exceptions are used to signal errors, allowing developers to write robust and error-handling code that can handle unexpected conditions and provide meaningful error messages to users.
What is the difference between a struct and a class in .NET?
A struct in .NET is a value type that directly contains its data and is stored on the stack. A class, on the other hand, is a reference type that stores a reference to the data and not the data itself, and is stored on the heap. Structs are typically used to represent small, simple objects, while classes are used to represent more complex objects with more functionality.
What is the difference between a sealed class and an abstract class in .NET?
An abstract class in .NET is a base class that provides a common implementation for its derived classes, but can still have abstract methods that must be implemented by its derived classes. A sealed class, on the other hand, is a class that cannot be inherited, providing a way to prevent further specialization of a class.
What is the difference between an event and a delegate in .NET?
An event in .NET is a mechanism for communicating between objects, allowing one object to notify another about something that has happened. Events are typically implemented using delegates, which provide a way to pass methods as arguments to other methods.
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