Top Advanced C# Interview Questions and Answers (2024)

Attribute is a powerful feature that plays an important role within the C# ecosystem as it adds metadata information to your assemblies.
Moreover, attributes are used to convey declarative information or metadata about various code elements such as: Assembly, Class, Method, Delegate, Enum, Event, Field, Interface, Property and Struct.
You can add declarative tag information to a program by using an attribute. To define, a declarative tag is depicted by square ([ ]) brackets placed above the element it is used for.
A declarative tag is placed using square brackets ([ ]) on top of the required code element and added to the code.

For instance, the Microsoft .Net Framework provides two types of attributes: the pre-defined and custom built attributes.

Pre-define attributes: AttributeUsage, Conditional, Obsolete.

Custom attributes: The Microsoft .Net Framework allows creating custom attributes that can be used to store declarative information and can be retrieved at run-time.

Reflection is used for obtaining type information at runtime, and when managed code can read its own metadata to explore assemblies. Also, it allows code to check other code within the same system.

The dynamic keyword was introduced in .NET 4.0.
There are two types of programming languages: strongly typed and dynamically typed.
Similarly, both reflection and dynamic are used when we want to work on an object during runtime.

Reflection can invite both public and private members of an object, whereas dynamic can invite only public members.

On the other hand, dynamic is model specific, in which case you need to use reflection.

Encapsulation is one of the basic features of an object-oriented programming language.

Moreover, encapsulation is accomplished using access tokens.
C# supports the following access tokens:

• General: Access to all code
• Private: Access only to members of the same class
• Protected: Access to members of the same class and its derived classes
• Internal: Access to current assembly
• Protected Internal: Access to the current assembly and types derived from the containing class

One of the most frequently asked questions in the list of C# interview questions is about destructors!
First of all, destructors are the techniques to destruct instances of classes.
Clearing the cache and removing all instances are very advantageous techniques.

In C#, you can never call them –one can’t destroy an object.

By using destructors, you can release memory if your program is using expensive external resources such as files, images, etc.

Destructors also have several properties, which are the following:

• Destructors can be used only in classes
• A destructor can be symbolized by using the tilde (~) operator
• A destructor won’t accept any parameters and access modifiers
• The garbage collector automatically invokes the destructor whenever the class objects are no longer needed in the application.

Property provides a flexible mechanism for reading, writing, or calculating the value of a special field.

Moreover, properties are actually private methods called accessors. Therefore, they make data easily accessible and help to increase its flexibility.

The C# property has two accessors: get property and set property accessors. A get accessor returns a property value, whereas a set accessor sets a new value. Additionally, the value keyword represents the value of a property.

In C# 9 and later, the init property accessor is used only during object creation, for instance.

The XML Schema language is called XML Schema Definition (XSD) and defines the structure of the XML document.

It’s used to describe the possible structure and content of the XML format.

Additionally, during the Serialization of the C# code, the classes are converted to XSD compatible format by xsd.exe.

To compile unsafe code, you must specify the /unsafe command-line switch with the command-line compiler.

For example, to compile a program called one.cs that contains unsafe code from the command line, issue the command: csc /unsafe one.cs

Follow the steps below.

Visual Studio IDE -> Enable unsafe code usage.
Open Solution Explorer -> Project properties.
Click the “Create” tab.
Select “Allow unsafe code”.