C# Keywords

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Microsoft Visual Studio 2008/.NET Framework 3.5

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C# Language Reference

C# 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.

The first table in this topic lists keywords that are reserved identifiers in any part of a C# program. The second table in this topic lists the contextual keywords in C#. Contextual keywords have special meaning only in a limited program context and can be used as identifiers outside that context. Generally, as new keywords are added to the C# language, they are added as contextual keywords in order to avoid breaking programs written in earlier versions.

abstract	event	new	struct
as	explicit	null	switch
base	extern	object	this
bool	false	operator	throw
break	finally	out	true
byte	fixed	override	try
case	float	params	typeof
catch	for	private	uint
char	foreach	protected	ulong
checked	goto	public	unchecked
class	if	readonly	unsafe
const	implicit	ref	ushort
continue	in	return	using
decimal	int	sbyte	virtual
default	interface	sealed	volatile
delegate	internal	short	void
do	is	sizeof	while
double	lock	stackalloc
else	long	static
enum	namespace	string

Contextual Keywords

A contextual keyword is used to provide a specific meaning in the code, but it is not a reserved word in C#. Some contextual keywords, such as partial and where, have special meanings in two or more contexts.

from	get	group
into	join	let
orderby	partial (type)	partial (method)
select	set	value
var	where (generic type constraint)	where (query clause)
yield

Concepts

C# Programming Guide

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C# Reference

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Event Delegates Add and Remove Accessor Methods

Frisky ... Akidan | Edit | Show History

(add and remove actually are listed above. It's under "Contextual Keywords")

The add and remove accessor methods (similar to the get and set for a property) are not included in the list above.

These allow you to intercept the calls when others wire up to your events in much the same was as get/set allows you to intercept calls to a property.

Below is some sample code that shows the accessor functions.

public event EventHandler OnClick
{
   add {
      Debug.WriteLine("add called");
      Click += value;
   }
   remove {
      Debug.WriteLine("remove called");
      Click -= value;
   }
}

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Descending is missing from the list of Contextual Keywords

Rick Strahl | Edit | Show History

The descending keyword (as in orderby ... descending) is not listed above.

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Missing Keywords

MMayerl ... gäst | Edit | Show History

There's actually a bunch of keywords missing!

As mentioned before, there are add and remove, and, of coure, descending and (!) ascending!

In addition to this, I miss the context-based alias-Keyword (as in extern alias).

Then, if I may ask, why don't you document the __makeref, __reftype, __refvalue und __arglist keywords?

And last but not least, though they are not really "keywords", I think that attribute path specifiers would fit here (assembly, module, method etc.)

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Why the length is 14 & 15?

variableF ... joelypolly | Edit | Show History

using System;

class Myclass
{
static void Main()
{
//int[] iPages = { 5,345345 };
//Console.WriteLine(iPages.ToString().Length); => This will output 14

//string[] iPages = { "5","adf","345345" };
//Console.WriteLine(iPages.ToString().Length); => This will output 15
}

}

I'm diving with C# data types, can someone please explain why the results are 14, 15 always?

Reply: If you view the iPages.ToString() you will get something like "System.String[]" Or "System.Int32[]" it doesn't actually print what is contained in the array

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