📝 What is Extension Method in C# and how to use them?
Extension methods allow you to add methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type. An extension method is a special kind of static method, but they are called as if they were instance methods on the extended type.
Extension methods allow you to add methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type. An extension method is a special kind of static method, but they are called as if they were instance methods on the extended type.
📝 What is sealed Class in C#?
When applied to a class, the sealed modifier prevents other classes from inheriting from it. In the following example, class B inherits from class A, but no class can inherit from class B.
You can also use the sealed modifier on a method or property that overrides a virtual method or property in a base class. This enables you to allow classes to derive from your class and prevent them from overriding specific virtual methods or properties.
Summary:
🔸 Once a class is defined as a sealed class, the class cannot be inherited.
🔸 Structs are also sealed.
When applied to a class, the sealed modifier prevents other classes from inheriting from it. In the following example, class B inherits from class A, but no class can inherit from class B.
You can also use the sealed modifier on a method or property that overrides a virtual method or property in a base class. This enables you to allow classes to derive from your class and prevent them from overriding specific virtual methods or properties.
Summary:
🔸 Once a class is defined as a sealed class, the class cannot be inherited.
🔸 Structs are also sealed.
📝 Why to use of the IDisposable interface?
The "primary" use of the IDisposable interface is to clean up unmanaged resources. Note the purpose of the Dispose pattern is to provide a mechanism to clean up both managed and unmanaged resources and when that occurs depends on how the Dispose method is being called.
The "primary" use of the IDisposable interface is to clean up unmanaged resources. Note the purpose of the Dispose pattern is to provide a mechanism to clean up both managed and unmanaged resources and when that occurs depends on how the Dispose method is being called.
📝 Explain the difference between Task and Thread in .NET
🔸 Thread represents an actual OS-level thread, with its own stack and kernel resources. Thread allows the highest degree of control; you can Abort() or Suspend() or Resume() a thread, you can observe its state, and you can set thread-level properties like the stack size, apartment state, or culture. ThreadPool is a wrapper around a pool of threads maintained by the CLR.
🔸 The Task class from the Task Parallel Library offers the best of both worlds. Like the ThreadPool, a task does not create its own OS thread. Instead, tasks are executed by a TaskScheduler; the default scheduler simply runs on the ThreadPool. Unlike the ThreadPool, Task also allows you to find out when it finishes, and (via the generic Task) to return a result.
🔸 Thread represents an actual OS-level thread, with its own stack and kernel resources. Thread allows the highest degree of control; you can Abort() or Suspend() or Resume() a thread, you can observe its state, and you can set thread-level properties like the stack size, apartment state, or culture. ThreadPool is a wrapper around a pool of threads maintained by the CLR.
🔸 The Task class from the Task Parallel Library offers the best of both worlds. Like the ThreadPool, a task does not create its own OS thread. Instead, tasks are executed by a TaskScheduler; the default scheduler simply runs on the ThreadPool. Unlike the ThreadPool, Task also allows you to find out when it finishes, and (via the generic Task) to return a result.
❓Explain the differences between an Interface and an Abstract Class in .NET?
An interface merely declares a contract or a behavior that implementing classes should have. It may declare only properties, methods, and events with no access modifiers. All the declared members must be implemented.
An abstract class provides a partial implementation for a functionality and some abstract/virtual members that must be implemented by the inheriting entities. It can declare fields too.
Neither interfaces nor abstract classes can be instantiated.
An interface merely declares a contract or a behavior that implementing classes should have. It may declare only properties, methods, and events with no access modifiers. All the declared members must be implemented.
An abstract class provides a partial implementation for a functionality and some abstract/virtual members that must be implemented by the inheriting entities. It can declare fields too.
Neither interfaces nor abstract classes can be instantiated.
Which of the following statements is not valid to create new object in C#?
Anonymous Quiz
11%
var a = new Int32();
6%
var a = new String();
58%
var a = new IComparable();
25%
var a = new [] {0};
❓Explain what inheritance is, and why it’s important
Inheritance is one of the most important concepts in object-oriented programming, together with encapsulation and polymorphism. Inheritance allows developers to create new classes that reuse, extend, and modify the behavior defined in other classes. This enables code reuse and speeds up development. With inheritance, developers can write and debug one class only once, and then reuse that same code as the basis for the new classes. The class whose members are inherited is called the base class, and the class that inherits those members is called the derived class. By default, all classes in .NET are inheritable.
Inheritance is one of the most important concepts in object-oriented programming, together with encapsulation and polymorphism. Inheritance allows developers to create new classes that reuse, extend, and modify the behavior defined in other classes. This enables code reuse and speeds up development. With inheritance, developers can write and debug one class only once, and then reuse that same code as the basis for the new classes. The class whose members are inherited is called the base class, and the class that inherits those members is called the derived class. By default, all classes in .NET are inheritable.
📝 What interface should your data structure implement to make the Where method work?
Implementing IEnumerable makes using foreach and where possible.
🔸 IEnumerable interface contains the System.Collections.Generic namespace.
🔸 IEnumerable interface is a generic interface which allows looping over generic or non-generic lists.
🔸 IEnumerable interface also works with linq query expression.
🔸 IEnumerable interface Returns an enumerator that iterates through the collection.
Implementing IEnumerable makes using foreach and where possible.
🔸 IEnumerable interface contains the System.Collections.Generic namespace.
🔸 IEnumerable interface is a generic interface which allows looping over generic or non-generic lists.
🔸 IEnumerable interface also works with linq query expression.
🔸 IEnumerable interface Returns an enumerator that iterates through the collection.
If you run C# executable file multiple times, multiple processes are created. If you want to have only one application process even if you launch multiple times, what can you use?
Anonymous Quiz
22%
Semaphore
41%
Mutex
10%
Critical Section
26%
C# lock
❓What do the following acronyms in .NET stand for: IL, CIL, MSIL, CLI and JIT?
IL, or Intermediate Language, is a CPU independent partially compiled code. IL code will be compiled to native machine code using current environmental properties by Just-In-Time compiler (JIT). JIT compiler translates the IL code to an assembly code and uses the CPU architecture of the target machine to execute a .NET application. In .NET, IL is called Common Intermediate Language (CIL), and in the early .NET days it was called Microsoft Intermediate Language (MSIL).
CLI, or Common Language Infrastructure, is an open specification developed by Microsoft. It is a compiled code library used for deployment, versioning, and security. In .NET there are two CLI types: process assemblies (EXE) and library assemblies (DLL). CLI assemblies contain code in CIL, and as mentioned, during compilation of CLI programming languages, the source code is translated into CIL code rather than into platform or processor specific object code.
To summary:
- When compiled, source code is first translated to IL (in .NET, that is CIL, and previously called MSIL).
- CIL is then assembled into a bytecode and a CLI assembly is created.
- Before code execution, CLI code is passed through the runtime’s JIT compiler to generate native machine code.
- The computer’s processor executes the native machine code.
IL, or Intermediate Language, is a CPU independent partially compiled code. IL code will be compiled to native machine code using current environmental properties by Just-In-Time compiler (JIT). JIT compiler translates the IL code to an assembly code and uses the CPU architecture of the target machine to execute a .NET application. In .NET, IL is called Common Intermediate Language (CIL), and in the early .NET days it was called Microsoft Intermediate Language (MSIL).
CLI, or Common Language Infrastructure, is an open specification developed by Microsoft. It is a compiled code library used for deployment, versioning, and security. In .NET there are two CLI types: process assemblies (EXE) and library assemblies (DLL). CLI assemblies contain code in CIL, and as mentioned, during compilation of CLI programming languages, the source code is translated into CIL code rather than into platform or processor specific object code.
To summary:
- When compiled, source code is first translated to IL (in .NET, that is CIL, and previously called MSIL).
- CIL is then assembled into a bytecode and a CLI assembly is created.
- Before code execution, CLI code is passed through the runtime’s JIT compiler to generate native machine code.
- The computer’s processor executes the native machine code.
📝 What is difference between late binding and early binding in C#?
🔸 Early Binding or Static Binding. The name itself describes that compiler knows about what kind of object it is, what are all the methods and properties it contains. As soon as you declared the object, .NET Intellisense will populate its methods and properties on click of the dot button.
🔸 Late Binding or Dynamic Binding. The name itself describes that compiler does not know what kind of object it is, what are all the methods and properties it contains. You have to declare it as an object, later you need get the type of the object, methods that are stored in it. Everything will be known at the run time.
🔸 Early Binding or Static Binding. The name itself describes that compiler knows about what kind of object it is, what are all the methods and properties it contains. As soon as you declared the object, .NET Intellisense will populate its methods and properties on click of the dot button.
🔸 Late Binding or Dynamic Binding. The name itself describes that compiler does not know what kind of object it is, what are all the methods and properties it contains. You have to declare it as an object, later you need get the type of the object, methods that are stored in it. Everything will be known at the run time.
Which of the following operators cannot use operator overloading?
Anonymous Quiz
13%
operator ++
11%
operator &
10%
operator ||
65%
operator true
❓Discuss what garbage collection is and how it works. Provide a code example of how you can enforce garbage collection in .NET
Garbage collection is a low-priority process that serves as an automatic memory manager which manages the allocation and release of memory for the applications. Each time a new object is created, the common language runtime allocates memory for that object from the managed Heap. As long as free memory space is available in the managed Heap,the runtime continues to allocate space for new objects. However, memory is not infinite, and once an application fills the Heap memory space, garbage collection comes into play to free some memory.
When the garbage collector performs a collection, it checks for objects in the managed Heap that are no longer being used by the application and performs the necessary operations to reclaim the memory. Garbage collection will stop all running threads, it will find all objects in the Heap that are not being accessed by the main program and delete them. It will then reorganize all the objects left in the Heap to make space and adjust all the Pointers to these objects in both the Stack and the Heap.
To enforce garbage collection in your code manually, you can run the following command (C#):
Garbage collection is a low-priority process that serves as an automatic memory manager which manages the allocation and release of memory for the applications. Each time a new object is created, the common language runtime allocates memory for that object from the managed Heap. As long as free memory space is available in the managed Heap,the runtime continues to allocate space for new objects. However, memory is not infinite, and once an application fills the Heap memory space, garbage collection comes into play to free some memory.
When the garbage collector performs a collection, it checks for objects in the managed Heap that are no longer being used by the application and performs the necessary operations to reclaim the memory. Garbage collection will stop all running threads, it will find all objects in the Heap that are not being accessed by the main program and delete them. It will then reorganize all the objects left in the Heap to make space and adjust all the Pointers to these objects in both the Stack and the Heap.
To enforce garbage collection in your code manually, you can run the following command (C#):
System.GC.Collect();
📝 Is operator overloading supported in C#?
A user-defined type can overload a predefined C# operator. That is, a type can provide the custom implementation of an operation in case one or both of the operands are of that type.
The above function implements the addition operator (+) for a user-defined class Box. It adds the attributes of two Box objects and returns the resultant Box object.
A user-defined type can overload a predefined C# operator. That is, a type can provide the custom implementation of an operation in case one or both of the operands are of that type.
The above function implements the addition operator (+) for a user-defined class Box. It adds the attributes of two Box objects and returns the resultant Box object.
In multithread programming, which of the followings is not using Thread Pool?
Anonymous Quiz
18%
BackgroundWorker class
26%
Asynchronous delegate
35%
Thread class
21%
Task class
❓Explain what LINQ is
LINQ is an acronym for Language Integrated Query, and was introduced with Visual Studio 2008. LINQ is a set of features that extends query capabilities to the .NET language syntax by adding sets of new standard query operators that allow data manipulation, regardless of the data source. Supported data sources are: .NET Framework collections, SQL Server databases, ADO.NET Datasets, XML documents, and any collection of objects that support
LINQ is an acronym for Language Integrated Query, and was introduced with Visual Studio 2008. LINQ is a set of features that extends query capabilities to the .NET language syntax by adding sets of new standard query operators that allow data manipulation, regardless of the data source. Supported data sources are: .NET Framework collections, SQL Server databases, ADO.NET Datasets, XML documents, and any collection of objects that support
IEnumerable or the generic IEnumerable<T> interface, in both C# and Visual Basic. In short, LINQ bridges the gap between the world of objects and the world of data.
📝 Why to use lock statement in C#?
The lock keyword ensures that one thread does not enter a critical section of code while another thread is in the critical section. If another thread tries to enter a locked code, it will wait, block, until the object is released.
The lock keyword calls Enter at the start of the block and Exit at the end of the block. lock keyword actually handles Monitor class at back end.
The lock keyword ensures that one thread does not enter a critical section of code while another thread is in the critical section. If another thread tries to enter a locked code, it will wait, block, until the object is released.
The lock keyword calls Enter at the start of the block and Exit at the end of the block. lock keyword actually handles Monitor class at back end.