C# basic syntax

C# is an object-oriented programming language. In the object-oriented programming method, a program consists of various objects that interact with each other. Objects of the same kind usually have the same type, or are in the same class.

For example, take the Rectangle object as an example. It has length and width properties. Depending on the design, it may need to accept these property values, calculate the area, and display the details.

Let's take a look at the implementation of a Rectangle class and discuss the basic syntax of C#:

Example

using System;
namespace RectangleApplication
{
    class Rectangle
    {
        // 成员变量
        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 ExecuteRectangle
    {
        static void Main(string[] args)
        {
            Rectangle r = new Rectangle();
            r.Acceptdetails();
            r.Display();
            Console.ReadLine();
        }
    }
}

Run Instance»

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##When the above code is compiled and executed, it produces the following results:

Length: 4.5
Width: 3.5
Area: 15.75

using Keywords

The first statement in any C# program is:

using System;

using Keywords are used in The program contains namespaces. A program can contain multiple using statements.

class Keywords

class Keywords are used to declare a class.

Comments in C

#Comments are used to explain the code. The compiler ignores commented entries. In C# programs, multi-line comments start with /* and end with the character */, as shown below:

/* This program demonstrates
The basic syntax of C# programming 
Language */

Single-line comments are represented by the '//' symbol. For example:

}//end class Rectangle

Member variables

Variables are attributes or data members of a class and are used to store data. In the above program, the Rectangle class has two member variables named length and width.

Member Function

A function is a series of statements that perform specified tasks. Member functions of a class are declared within the class. Our example class Rectangle contains three member functions: AcceptDetails, GetArea and Display.

Instantiate a class

In the above program, class ExecuteRectangle is a class that contains the Main() method and instantiation of Rectangle Class of classes.

Identifier

Identifier is used to identify a class, variable, function or any other user-defined item. In C#, class naming must follow the following basic rules:

The identifier must start with a letter and can be followed by a series of letters, numbers (0 - 9) or underscores (_ ). The first character in the identifier cannot be a number.
The identifier must not contain any embedded spaces or symbols, such as ? - +! @ # % ^ & * ( ) [ ] { } . ; : " ' / \. But , an underscore ( _ ) may be used. The
## identifier cannot be a C# keyword

The following table lists the reservations in C#. Keywords (Reserved Keywords) and contextual keywords (Contextual Keywords):

保留关键字
abstract	as	base	bool	break	byte	case
catch	char	checked	class	const	continue	decimal
default	delegate	do	double	else	enum	event
explicit	extern	false	finally	fixed	float	for
foreach	goto	if	implicit	in	in (generic modifier)	int
interface	internal	is	lock	long	namespace	new
null	object	operator	out	out (generic modifier)	override	params
private	protected	public	readonly	ref	return	sbyte
sealed	short	sizeof	stackalloc	static	string	struct
switch	this	throw	true	try	typeof	uint
ulong	unchecked	unsafe	ushort	using	virtual	void
volatile	while
上下文关键字
add	alias	ascending	descending	dynamic	from	get
global	group	into	join	let	orderby	partial (type)
partial (method)	remove	select	set

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