C# 4 and .NET 4

58 ❘ ChaPTer 2 cOre c#
directive can be used to restore the match. You can also use the syntax #line default to restore the line to
the default line numbering:
#line 164 "Core.cs" // We happen to know this is line 164 in the file
// Core.cs, before the intermediate
// package mangles it.
// later on
#line default
// restores default line numbering
#pragma
The #pragma directive can either suppress or restore specific compiler warnings. Unlike command-line
options, the #pragma directive can be implemented on a class or method level, allowing fine-grained
control of what warnings are suppressed and when. The following example disables the “field not used”
warning and then restores it after the MyClass class compiles:
#pragma warning disable 169
public class MyClass
{
int neverUsedField;
}
#pragma warning restore 169
C# Programming guidelines
The final section of this chapter supplies the guidelines you need to bear in mind when writing C#
programs.
rules for identifiers
This section examines the rules governing what names you can use for variables, classes, methods, and
so on. Note that the rules presented in this section are not merely guidelines: they are enforced by the C#
compiler.
Identifiers are the names you give to variables, to user-defined types such as classes and structs, and to
members of these types. Identifiers are case-sensitive, so, for example, variables named interestRate and
InterestRate would be recognized as different variables. Following are a few rules determining what
identifiers you can use in C#:
➤
➤
They must begin with a letter or underscore, although they can contain numeric characters.
You can’t use C# keywords as identifiers.
The following table lists the C# reserved keywords.
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
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