BASIC OF C# PROGRAMMING FOR BEGINNERS – PART : I

BASIC OF C# PROGRAMMING FOR BEGINNERS – PART : I

Introduction

In this article we see the Basic of concepts of C#     

•   Identifier
•   Keywords
•   Variables

Identifier 

An identifier, in C#, is the user-defined name of a program element. It can be a namespace, class, method, variable or interface. Identifiers in C# are case-sensitive.

An identifier name should indicate the meaning and usage of the element being referred.

C# is a programming language that is compiled and has its implementation such that the identifiers are only compile-time entities. During run time, each identifier will be referred by its reference to the memory address and offset the compiler assigned to its textual identifier token.

Microsoft recommends the use of Camel or Pascal notations, along with semantics, for was used prior to .NET programming. For example, "employeeAge" might represent Camel notation wherein the first letter of all the words is capitalized except the first word. Camel notation is used to name private members, fields and parameters. "EmployeeAge" is an identifier in Pascal notation, as all the words in the identifier begin with an upper-case letter.

The rules to be followed while using an identifier include:

• It can start only with a letter of the alphabet or underscore(_), but not a number
• It can be a combination of numbers, letters, connectors, Unicode escape sequence, etc.
• It cannot be a C# keyword
• It should not contain white space
• It cannot have more than 511 characters
• It cannot have two consecutive underscores in its name because such identifiers are used for the implementation
• More than one identifier with the same name cannot be declared within a single scope

An identifier prefixed with "@" is called a verbatim identifier. Although prefixing "@" allows for the use of keywords, which helps in interfacing with other programming languages, it is not a recommended practice.

Keywords
Keywords are predefined, reserved identifiers that have special meanings to the compiler. They cannot be used as identifiers in your program unless they include @ as a prefix. For example, @if is a valid identifier but if is not because if is a keyword.

Following Table list the different reserved and contextual keywords

Reserved Keywords
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	int	interface
internal	is	lock	long	namespace	new	null
object	operator	out	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	volatile	void	while

Contextual Keywords
add	alias	ascending	descending	dynamic	from	get
global	group	into	join	let	orderby	partial
remove	select	set	value	where	yield

Variables

A variable, in C#, refers to a location in memory in which an application can store its data. Variables are used to store the result of calculations and hold the values that can change during the execution of a program. Variables are also used to place and retrieve the data forms an expression.

C# language is designed to be "type-safe," which helps ensure that the value stored in a variable is of the appropriate type. The type of a variable specifies what kind of data it can hold. This feature helps to reduce the burden from the programmer by guaranteeing the data's type safety.

C# expects the data type of a variable to be specified during declaration, which helps to allocate the memory for the variable during run time. In order to maintain the integrity of the data stored in a variable, C# defines a set of rules that dictate the permissible operations that can be performed on the variable.

For example

            int  x;

            x=25;

In this example we declare a x variable with integer data type and assign a value of 25 by using = operator

A variable can be declared as local or class variable. Local Variable exist within the scope of a given method in a class, Class variables exist the entire Lifetime of the object instance of the class