C# BASIC SYNTAX

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, more often, are said to be in the same class.

For example, let us consider an object Rectangle. It has attributes such as length and width. Depending upon the design, it may need ways for accepting the values of these attributes, calculating area, and display details.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Demo
{
    class Rectangle
    {
        // member variables
        double length;
        double width;
        public void Acceptdetails()
        {
            length = 4.5;
            width = 3.5;
        }
        public double GetArea()
        {
            return length * width;
        }
        public void Display()
        {
            Console.WriteLine("Length: {0}", length);
            Console.WriteLine("Width: {0}", width);
            Console.WriteLine("Area: {0}", GetArea());
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Rectangle r = new Rectangle();
            r.Acceptdetails();
            r.Display();
            Console.ReadLine();
            // Length: 4.5
            // Width: 3.5
            // Area: 15.75
        }
    }
}

The using keyword is used for including the namespaces in the program. A program can include multiple using statements.

The class keyword is used for declaring a class.

Comments are used for explaining code. Compiler ignores the comment entries. The multiline comments in C# programs start with /* and terminates with the characters

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

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

In the preceding program, the class ExecuteRectangle is used as a class, which contains the Main() method and instantiates the Rectangle class

An identifier is a name used to identify a class, variable, function, or any other userdefined 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 like ? - +! @ # % ^ & * ( ) [ ] { } . ; : ” ’ / and . However, an underscore ( _ ) can be used.
• It should not be a C# keyword