Prepare for the most anticipated C# interview questions and answers for experienced professionals to increase your chances of landing a job at the top companies that use C# in their tech stacks, such as Accenture, Google, Delivery Hero, Wipro, Infosys, HCL, TCs, Microsoft, Stack Overflow, Intuit, and Trustpilot.
C# is a programming language ideal for general purposes as it encompasses several disciplines such as object-oriented programming, component-oriented programming, and static and strong typing. C# is popularly used in the ASP.NET framework as it is ideal for creating web applications, websites, and games.
In this article, we present the most frequently asked C# interview questions and answers for experienced professionals.
The key concepts in the following list of C# interview questions for experienced professionals are explained simply and easily to help you ace your next job interview.
You can carry out exception handling using the following four keywords in C#:
You can implement encapsulation by using access specifiers that define the scope and visibility of a class member. Some access specifiers are as follows:
Overloading and overriding are concepts in object-oriented programming that allow methods to be redefined or extended in a class. However, they differ in their purpose and implementation.
| Aspect |
Overloading | Overriding |
| Definition | Occurs when two or more methods in the same class have the same name but different parameters (type, number, or both). | Occurs when a subclass provides a specific implementation for a method defined in its superclass. |
| Purpose | Provides multiple ways to perform a similar action depending on different input parameters. | Allows a subclass to offer a specific implementation that differs from the superclass method. |
| Polymorphism Type | Compile-time polymorphism. | Runtime polymorphism through dynamic method dispatch. |
| Method Signatures | Involves different method signatures within the same class. | Involves the same method signature in both superclass and subclass. |
| Resolution | Resolved at compile-time. | Resolved at runtime. |
These differences highlight the distinct roles that overloading and overriding play in enhancing the flexibility and functionality of object-oriented programming.
In C#, in method hiding, which is also known as method shadowing, the base class implementation of a method is hidden from the derived class through redefinition in the derived class. To make a method private, you can use the new keyword in the derived class. If you do not use the new keyword, the compiler will run the code, but it will put a warning. In method shadowing, the base class method is not marked as virtual and the derived class method does not use the new keyword.
Generics promote the use of parameterized types, allowing you to write flexible and reusable code. With generics, you can create collection classes that work with any data type, ensuring type safety and reducing the need for casting.
In .NET, the System.Collections.Generic namespace is utilized to create generic collections instead of using non-generic classes. This approach improves performance and code clarity by specifying the type of objects the collection will hold, eliminating type mismatches, and enhancing maintainability. By leveraging generics, developers can create robust, type-safe collections, improving both the flexibility and efficiency of their code.
You can de-couple tightly linked classes using the dependency injection. Thus, it reduces the direct dependency of classes upon each other. You can achieve dependency injection via the following:
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This is one of the most commonly asked C# interview questions and answers for experienced professionals. Polymorphism is one of the three main pillars of object-oriented programming after encapsulation and inheritance.
The term polymorphism means “many shapes.” It occurs when there are many classes related to each other by inheritance.
For instance, at runtime, derived class objects may be treated as base class objects in places like collections/ method parameters/ arrays. In such polymorphism, declared and runtime types of objects are different. Thus, polymorphism allows a class to have multiple implementations with the same name.
No, you cannot serialize a hashtable in .NET. This is because the .NET Framework does not support the serialization of objects that implement the IDictionary interface, which includes Hashtable. As a result, attempting to serialize a hashtable will result in an error. For scenarios requiring serialization, consider using alternative data structures such as  Dictionary<tkey, tvalue>, which provides better serialization support in .NET.</tkey,>
A compiled library (DLL) containing localizable resources specific to a given culture like strings and bitmaps is referred to as a Satellite Assembly. You can use satellite assemblies while creating a multilingual UI application.
Interface inheritance is when a class inherits only the signatures of the functions from another class. It is also called type inheritance/ subtyping. It allows code reuse and polymorphism. The main advantage of interface inheritance is that it reduces coupling and implementation dependencies.
You can answer this C# interview question for experienced professionals by stating that the major advantages of using partial classes are
String Interpolation in C# allows you to create and format strings in a readable and convenient manner. By using the $ special character before a string, you can include expressions within curly braces {} that are dynamically evaluated and replaced with their string representations during runtime.
For Example:
string name = “John”;
int age = 30;
string message = $”Hello, my name is {name} and I am {age} years old.”;
In this example, the placeholders {name} and {age} are replaced with the values of the variables, resulting in a formatted string. String interpolation simplifies the process of formatting strings without needing complex concatenation or format methods.
While covariance allows a method to have a return type, a subtype of the one defined in the delegate, contravariance allows a method to have a parameter type, i.e., a base type of the one defined in the delegate type.
You can answer this C# interview question for experienced professionals by stating that classes and structs have the following in common:
The key differences between structs and classes are as follows:
| Point of Differences | Structs | Classes |
| Default access modifier | It is public in Structs | It is private |
| Memory allocation | They are generally allocated on the stack, meaning a copy is made when the struct is assigned to a new variable | They are reference types and thus are allocated on the heap. When a class is assigned to a new variable, a reference is assigned to the same object |
| Inheritance | It does not support inheritance | You can create a hierarchy of classes and reuse the code because classes support inheritance |
| Use cases | They are used for small and simple data structures with short lifetime | They are typically used for complex data structures that rely on inheritance |
| Performance | For small and short-term projects, they offer better performance | They are more efficient for large and long-term projects |
With these C# interview questions for experienced professionals, you can understand how well prepared you are for the technical interview. You can use these questions to practice and brush up on certain fundamental concepts.
You should be well-versed in data structures and algorithms to ace the coding C# interview questions in technical interview rounds.
With 3 years of experience, you are expected to have the basic, fundamental knowledge of C# concepts. You can use these questions to understand to gauge your preparedness.
These C# interview questions cover important concepts and more advanced C# topics like method handling, memory management, and concurrency among others. Use these C# questions for professionals with 5 years experience to practice some of the more advanced concepts and topics.
If you are applying for senior C# developer roles, you should practice the following advanced C# interview questions to outperform the competition.
In addition to these C# interview questions for experienced professionals, you must practice mock interviews to nail the most challenging technical interviews.
Preparing for technical interviews, especially the challenging ones, puts you on the path to becoming a better software professional with improved coding, problem-solving, and behavioral skills. You build more confidence for even the toughest interviews.
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You should thoroughly practice control statements, arrays, functions, object classes, properties, inheritance, abstraction, polymorphism, CLR, CLS, CTS, and strings exception handling to ace C# interview questions and answers for experienced professionals.
You must get well-versed in basic and advanced concepts of C#. Practice the most anticipated interview questions, and practice mock interviews. You must practice multiple coding problems to improve your speed and accuracy.
The key difference between C and C# is that the C language can be executed cross-platform, whereas the .NET framework is required to execute the C# language. In the C language, garbage collection is not available, but C# features garbage collection managed by Common Language Runtime (CLR).
Several top companies use C# interview questions and answers for experienced professionals, including Google, Wipro, Infosys, Accenture, JP Morgan, HCL, TCS, and Google.
The salaries of C# developers range from $60,000 to $160,000 in the United States, and the average salary is $80,000 (Source: comparably.com).
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