The C Keywords

In addition to the keywords, C# defines a set of words that have unique meanings when they are used in certain situations. These are called contextual keywords . They include get , set , yield , value , where , and partial . Because they are not reserved words, outside their context they can be used as names for other program elements, but good practice suggests that it is better not to do so.

Identifiers

In C#, an identifier is a name assigned to a method, a variable, or any other user -defined item. Identifiers can be from one to several characters long. Variable names may start with any letter of the alphabet or an underscore. Next may be a letter, a digit, or an underscore. The underscore can be used to enhance the readability of a variable name, as in line_count . However, identifiers containing two consecutive underscores, such as max_ _value , are reserved for use by the compiler. Uppercase and lowercase are different; that is, to C#, myvar and MyVar are separate names. Here are some examples of acceptable identifiers:

// Demonstrate an @ identifier. using System; class IdTest { public static void Main() { int @if; // use if as an identifier for(@if = 0; @if < 10; @if++) Console.WriteLine("@if is " + @if); } }

@if is 0 @if is 1 @if is 2 @if is 3 @if is 4 @if is 5 @if is 6 @if is 7 @if is 8 @if is 9