.NET Core

• .NET Core is compatible with a variety of operating systems, including Windows, Linux, and Mac OS. (Cross Platform)

• .NET Core has built-in dependency injection.

• .NET Core has support for microservices. , NET Core allows a mix of technologies that can be minimalized for each microservice.

• .NET Core is an open-source platform.

.NET Framework

• .NET Framework is compatible with Windows OS(operating system) only .

• .NET Framework has no built-in dependency injection - need to use external libraries such as Ninject and Unity

• .NET Framework it does not allow for the construction and deployment of microservices in multiple languages.

• .NET Framework includes certain open source components.

• Extension methods allow developers to add a method to existing types without changing the original source code. This allows them to extend the functionality of the method.

• An extension method is a static method and uses the <this> keyword.

• C# delegates are similar to pointers to functions, in C or C++.

• A delegate is a reference type variable that holds the reference to a method

• Delegates are mainly used in implementing the call-back methods and events.

• Delegates can be chained together as two or more methods can be called on a single event.

• Multicasting of a delegate.

  1. Delegate objects can be composed using the "+" operator. A composed delegate calls the two delegates it was composed from.

  2. Only delegates of the same type can be composed.

  3. The "-" operator can be used to remove a component delegate from a composed delegate.

  4. Using this property of delegates you can create an invocation list of methods that will be called when a delegate is invoked.

• Generic is a concept that allows us to define classes and methods with placeholder

• Generics allow you to define type-safe data structures, without committing to actual data types.

• To define a class or method as generic, we need to use a type parameter as a placeholder with angle (<>) brackets.

• String is present in System namespace.

• A string object is immutable, meaning that it cannot be changed after it’s created.

• Any operation that tries to modify the string object will simply create a new string object.

• String is thread safe

• StringBuilder is present in System.Text namespace.

• StringBuilder object is mutable and can be modified 

• StringBuilder is not thread safe (not synchronized, not locked)

• StringBuilder has overhead, so string is faster for limited concatenations.

• If you are going to append or modify thousands of times (usually not the case) then StringBuilder is faster in those scenarios.

• StringBuffer is a mutable (no StringBuffer in C#, its available in Java)

• StringBuffer is thread safe (synchronized., locked)

• StringBuffer is slower than StringBuilder as it need to lock and release locks for threads

In simple words String is an immutable. StringBuffer is a mutable and synchronized. StringBuilder is mutable but not synchronized. 

• Abstract classes: These provide a common definition for a base class that other classes can be derived from

• Static classes: These contain static items that can only interact with other static items

• Partial classes: These are portions of a class that a compiler can combine to form a complete class

• Sealed classes: These cannot be inherited by any class but can be instantiated

const

• They can not be declared as static (they are implicitly static)

• The value of constant is evaluated at compile time

• constants are initialized at declaration only

readonly

• They can be either instance-level or static

• The value is evaluated at run time

• readonly can be initialized in declaration or by code in the constructor