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CBASIC Learning C# basics

Tags: C#, Csharp, C# fundamentals, C# basics

These lessons are designed to keep you engaged with the process of learning C# basics. Our main focus will be on learning C# basics. 

Lesson 5 Basic Syntax

Attachment: ConsoleApp2.zip

C# is an object-oriented programming language. In Object-Oriented Programming methodology, a program consists of various objects that interact with each other by means of actions. The actions that an object may take are called methods. Objects of the same kind are said to have the same type or, are said to be in the same class.

For example, let us consider a Cube object. It has attributes such as length, width and height. Depending upon the design, it may need ways for accepting the values of these attributes, calculating the volume, and displaying details.

Let us look at implementation of a Cube class and discuss C# basic syntax:

using System;

namespace ConsoleApp2

{

    class Cube

    {

        //variables used

        double length;

        double width;

        double height;

        public void Details()

        {

            Console.Write("Enter length: ");

            length = double.Parse(Console.ReadLine());

            Console.Write("Enter width: ");

            width = double.Parse(Console.ReadLine());

            Console.Write("Enter height: ");

            height = double.Parse(Console.ReadLine());

            Console.WriteLine("");

        }

        public double CalcVolume()

        {

            return length * width * height;

        }

        public void Display()

        {

            //Console.WriteLine("Length: {0}", length);

            //Console.WriteLine("Width: {0}", width);

            //Console.WriteLine("Height: {0}", height);

            //Console.WriteLine("Volume: {0}", CalcVolume());

            Console.WriteLine($"Length: {length}");

            Console.WriteLine($"Width: {width}");

            Console.WriteLine($"Height: {height}");

            Console.WriteLine($"Volume: {CalcVolume()}");

        }

    }

    class ExecuteCube

    {

        static void Main(string[] args)

        {

            Cube r = new Cube();

            r.Details();

            r.Display();

            Console.ReadLine();

        }

    }

}

When the above code is compiled and executed, it produces the following result

The using Keyword

The first statement in any C# program is using System; The using keyword is used for including the namespaces in the program. A program can include multiple using statements.

The class Keyword

The class keyword is used for declaring a class.

Comments in C#

Comments are used for explaining code. Compilers ignore the comment entries. The multiline comments in C# programs start with /* and terminates with the characters */ as shown below:

/* This program demonstrates

The basic syntax of C# programming 

Language */

Single-line comments are indicated by the '//' symbol.

For example - //variables used

Member Variables

Variables are attributes or data members of a class, used for storing data. In the preceding program, the Cube class has three member variables named length, width and height.

Member Functions

Functions are set of statements that perform a specific task. The member functions of a class are declared within the class. Our sample class Cube contains three member functions: Details, CalcVolume and Display.

Instantiating a Class

In the preceding program, the class ExecuteCube contains the Main() method and instantiates the Cube class.

Identifiers

An identifier is a name used to identify a class, variable, function, or any other user-defined item. The basic rules for naming classes in C# are as follows:

• A name must begin with a letter that could be followed by a sequence of letters, digits (0 - 9) or underscore. The first character in an identifier cannot be a digit.
• It must not contain any embedded space or symbol such as? - + ! @ # % ^ & * ( ) [ ] { } . ; : " ' / and \. However, an underscore ( _ ) can be used.
• It should not be a C# keyword.

C# Keywords

Keywords are reserved words predefined to the C# compiler. These keywords cannot be used as identifiers. However, if you want to use these keywords as identifiers, you may prefix the keyword with the @ character.

In C#, some identifiers have special meaning in context of code, such as get and set are called contextual keywords.

The following table lists the reserved keywords and contextual keywords in C#:

Next -> CBASIC Lesson 6 Data Types