C# allows using pointer variables in a function of code block when it is marked by the unsafe modifier. The unsafe code or the unmanaged code is a code block that uses a pointer variable. Pointers A pointer is a variable whose value is the address of another variable i.e., the direct address o

We discussed that delegates are used to reference any methods that has the same signature as that of the delegate. In other words, you can call a method that can be referenced by a delegate using that delegate object. Anonymous methods provide a technique to pass a code block as a delegate para

Generics allow you to define the specification of the data type of programming elements in a class or a method, until it is actually used in the program. In other words, generics allow you to write a class or method that can work with any data type. You write the specifications for the class or

Collection classes are specialized classes for data storage and retrieval. These classes provide support for stacks, queues, lists, and hash tables. Most collection classes implement the same interfaces. Collection classes serve various purposes, such as allocating memory dynamically to element

Events are user actions such as key press, clicks, mouse movements, etc., or some occurrence such as system generated notifications. Applications need to respond to events when they occur. For example, interrupts. Events are used for inter-process communication. Using Delegates with Events The

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. The reference can be changed at runtime. Delegates are especially used for implementing events and the call-back methods. All delegates are implicitly de

An indexer allows an object to be indexed such as an array. When you define an indexer for a class, this class behaves similar to a virtual array. You can then access the instance of this class using the array access operator ([ ]). Syntax A one dimensional indexer has the following syntax &min

Properties are named members of classes, structures, and interfaces. Member variables or methods in a class or structures are called Fields. Properties are an extension of fields and are accessed using the same syntax. They use accessors through which the values of the private fields can be rea

Reflection objects are used for obtaining type information at runtime. The classes that give access to the metadata of a running program are in the System.Reflection namespace. The System.Reflection namespace contains classes that allow you to obtain information about the application and to dyn

An attribute is a declarative tag that is used to convey information to runtime about the behaviors of various elements like classes, methods, structures, enumerators, assemblies etc. in your program. You can add declarative information to a program by using an attribute. A declarative tag is d

A file is a collection of data stored in a disk with a specific name and a directory path. When a file is opened for reading or writing, it becomes a stream. The stream is basically the sequence of bytes passing through the communication path. There are two main streams: the input stream and th

An exception is a problem that arises during the execution of a program. A C# exception is a response to an exceptional circumstance that arises while a program is running, such as an attempt to divide by zero. Exceptions provide a way to transfer control from one part of a program to another.

A regular expression is a pattern that could be matched against an input text. The .Net framework provides a regular expression engine that allows such matching. A pattern consists of one or more character literals, operators, or constructs. Constructs for Defining Regular Expressions There are

The preprocessor directives give instruction to the compiler to preprocess the information before actual compilation starts. All preprocessor directives begin with #, and only white-space characters may appear before a preprocessor directive on a line. Preprocessor directives are not statements

A namespace is designed for providing a way to keep one set of names separate from another. The class names declared in one namespace does not conflict with the same class names declared in another. Defining a Namespace A namespace definition begins with the keyword namespace followed by the na

An interface is defined as a syntactical contract that all the classes inheriting the interface should follow. The interface defines the what part of the syntactical contract and the deriving classes define the how part of the syntactical contract. Interfaces define properties, methods, and eve

You can redefine or overload most of the built-in operators available in C#. Thus a programmer can use operators with user-defined types as well. Overloaded operators are functions with special names the keyword operator followed by the symbol for the operator being defined. similar to any othe

The word polymorphism means having many forms. In object-oriented programming paradigm, polymorphism is often expressed as one interface, multiple functions. Polymorphism can be static or dynamic. In static polymorphism, the response to a function is determined at the compile time. In dynamic p

One of the most important concepts in object-oriented programming is inheritance. Inheritance allows us to define a class in terms of another class, which makes it easier to create and maintain an application. This also provides an opportunity to reuse the code functionality and speeds up imple

When you define a class, you define a blueprint for a data type. This does not actually define any data, but it does define what the class name means. That is, what an object of the class consists of and what operations can be performed on that object. Objects are instances of a class. The meth