C^#

Language Specification

Version 1.2

Notice

© 1999-2003 Microsoft Corporation. All rights reserved.

Microsoft, Windows, Visual Basic, Visual C#, and Visual C++ are either registered trademarks or trademarks of Microsoft Corporation in the U.S.A. and/or other countries/regions.

Other product and company names mentioned herein may be the trademarks of their respective owners.

Table of Contents

• 1. Introduction

• 1.1 Hello world
• 1.2 Program structure
• 1.3 Types and variables
• 1.4 Expressions
• 1.5 Statements
• 1.6 Classes and objects
• 1.6.1 Members
• 1.6.2 Accessibility
• 1.6.3 Base classes
• 1.6.4 Fields
• 1.6.5 Methods
• 1.6.5.1 Parameters
• 1.6.5.2 Method body and local variables
• 1.6.5.3 Static and instance methods
• 1.6.5.4 Virtual, override, and abstract methods
• 1.6.5.5 Method overloading
• 1.6.6 Other function members
• 1.6.6.1 Constructors
• 1.6.6.2 Properties
• 1.6.6.3 Indexers
• 1.6.6.4 Events
• 1.6.6.5 Operators
• 1.6.6.6 Destructors
• 1.7 Structs
• 1.8 Arrays
1.9 Interfaces
• 1.10 Enums
• 1.11 Delegates
• 1.12 Attributes

• 2. Lexical structure

• 2.1 Programs
• 2.2 Grammars
• 2.2.1 Grammar notation
• 2.2.2 Lexical grammar
• 2.2.3 Syntactic grammar
• 2.3 Lexical analysis
• 2.3.1 Line terminators
• 2.3.2 Comments
• 2.3.3 White space
• 2.4 Tokens
• 2.4.1 Unicode character escape sequences
• 2.4.2 Identifiers
• 2.4.3 Keywords
• 2.4.4 Literals
• 2.4.4.1 Boolean literals
• 2.4.4.2 Integer literals
• 2.4.4.3 Real literals
• 2.4.4.4 Character literals
• 2.4.4.5 String literals
• 2.4.4.6 The null literal
• 2.4.5 Operators and punctuators
• 2.5 Pre-processing directives
• 2.5.1 Conditional compilation symbols
• 2.5.2 Pre-processing expressions
• 2.5.3 Declaration directives
• 2.5.4 Conditional compilation directives
• 2.5.5 Diagnostic directives
• 2.5.6 Region directives
• 2.5.7 Line directives

• 3. Basic concepts

• 3.1 Application Startup
• 3.2 Application termination
• 3.3 Declarations
• 3.4 Members
• 3.4.1 Namespace members
• 3.4.2 Struct members
• 3.4.3 Enumeration members
• 3.4.4 Class members
• 3.4.5 Interface members
• 3.4.6 Array members
• 3.4.7 Delegate members
• 3.5 Member access
• 3.5.1 Declared accessibility
• 3.5.2 Accessibility domains
• 3.5.3 Protected access for instance members
• 3.5.4 Accessibility constraints
• 3.6 Signatures and overloading
• 3.7 Scopes
• 3.7.1 Name hiding
• 3.7.1.1 Hiding through nesting
• 3.7.1.2 Hiding through inheritance
• 3.8 Namespace and type names
• 3.8.1 Fully qualified names
• 3.9 Automatic memory management
• 3.10 Execution order

• 4. Types

• 4.1 Value types
• 4.1.1 The System.ValueType type
• 4.1.2 Default constructors
• 4.1.3 Struct types
• 4.1.4 Simple types
• 4.1.5 Integral types
• 4.1.6 Floating point types
• 4.1.7 The decimal type
• 4.1.8 The bool type
• 4.1.9 Enumeration types
• 4.2 Reference types
• 4.2.1 Class types
• 4.2.2 The object type
• 4.2.3 The string type
• 4.2.4 Interface types
• 4.2.5 Array types
• 4.2.6 Delegate types
• 4.3 Boxing and unboxing
• 4.3.1 Boxing conversions
• 4.3.2 Unboxing conversions

• 5. Variables

• 5.1 Variable categories
• 5.1.1 Static variables
• 5.1.2 Instance variables
• 5.1.2.1 Instance variables in classes
• 5.1.2.2 Instance variables in structs
• 5.1.3 Array elements
• 5.1.4 Value parameters
• 5.1.5 Reference parameters
• 5.1.6 Output parameters
• 5.1.7 Local variables
• 5.2 Default values
• 5.3 Definite assignment
• 5.3.1 Initially assigned variables
• 5.3.2 Initially unassigned variables
• 5.3.3 Precise rules for determining definite assignment
• 5.3.3.1 General rules for statements
• 5.3.3.2 Block statements, checked, and unchecked statements
• 5.3.3.3 Expression statements
• 5.3.3.4 Declaration statements
• 5.3.3.5 If statements
• 5.3.3.6 Switch statements
• 5.3.3.7 While statements
• 5.3.3.8 Do statements
• 5.3.3.9 For statements
• 5.3.3.10 Break, continue, and goto statements
• 5.3.3.11 Throw statements
• 5.3.3.12 Return statements
• 5.3.3.13 Try-catch statements
• 5.3.3.14 Try-finally statements
• 5.3.3.15 Try-catch-finally statements
• 5.3.3.16 Foreach statements
• 5.3.3.17 Using statements
• 5.3.3.18 Lock statements
• 5.3.3.19 General rules for simple expressions
• 5.3.3.20 General rules for expressions with embedded expressions
• 5.3.3.21 Invocation expressions and object creation expressions
• 5.3.3.22 Simple assignment expressions
• 5.3.3.23 && expressions
• 5.3.3.24 || expressions
• 5.3.3.25 ! expressions
• 5.3.3.26 ?: expressions
• 5.4 Variable references
• 5.5 Atomicity of variable references

• 6. Conversions

• 6.1 Implicit conversions
• 6.1.1 Identity conversion
• 6.1.2 Implicit numeric conversions
• 6.1.3 Implicit enumeration conversions
• 6.1.4 Implicit reference conversions
• 6.1.5 Boxing conversions
• 6.1.6 Implicit constant expression conversions
• 6.1.7 User-defined implicit conversions
• 6.2 Explicit conversions
• 6.2.1 Explicit numeric conversions
• 6.2.2 Explicit enumeration conversions
• 6.2.3 Explicit reference conversions
• 6.2.4 Unboxing conversions
• 6.2.5 User-defined explicit conversions
• 6.3 Standard conversions
• 6.3.1 Standard implicit conversions
• 6.3.2 Standard explicit conversions
• 6.4 User-defined conversions
• 6.4.1 Permitted user-defined conversions
• 6.4.2 Evaluation of user-defined conversions
• 6.4.3 User-defined implicit conversions
• 6.4.4 User-defined explicit conversions

• 7. Expressions

• 7.1 Expression classifications
• 7.1.1 Values of expressions
• 7.2 Operators
• 7.2.1 Operator precedence and associativity
• 7.2.2 Operator overloading
• 7.2.3 Unary operator overload resolution
• 7.2.4 Binary operator overload resolution
• 7.2.5 Candidate user-defined operators
• 7.2.6 Numeric promotions
• 7.2.6.1 Unary numeric promotions
• 7.2.6.2 Binary numeric promotions
• 7.3 Member lookup
• 7.3.1 Base types
• 7.4 Function members
• 7.4.1 Argument lists
• 7.4.2 Overload resolution
• 7.4.2.1 Applicable function member
• 7.4.2.2 Better function member
• 7.4.2.3 Better conversion
• 7.4.3 Function member invocation
• 7.4.3.1 Invocations on boxed instances
• 7.5 Primary expressions
• 7.5.1 Literals
• 7.5.2 Simple names
• 7.5.2.1 Invariant meaning in blocks
• 7.5.3 Parenthesized expressions
• 7.5.4 Member access
• 7.5.4.1 Identical simple names and type names
• 7.5.5 Invocation expressions
• 7.5.5.1 Method invocations
• 7.5.5.2 Delegate invocations
• 7.5.6 Element access
• 7.5.6.1 Array access
• 7.5.6.2 Indexer access
• 7.5.7 This access
• 7.5.8 Base access
• 7.5.9 Postfix increment and decrement operators
• 7.5.10 The new operator
• 7.5.10.1 Object creation expressions
• 7.5.10.2 Array creation expressions
• 7.5.10.3 Delegate creation expressions
• 7.5.11 The typeof operator
• 7.5.12 The checked and unchecked operators
• 7.6 Unary operators
• 7.6.1 Unary plus operator
• 7.6.2 Unary minus operator
• 7.6.3 Logical negation operator
• 7.6.4 Bitwise complement operator
• 7.6.5 Prefix increment and decrement operators
• 7.6.6 Cast expressions
• 7.7 Arithmetic operators
• 7.7.1 Multiplication operator
• 7.7.2 Division operator
• 7.7.3 Remainder operator
• 7.7.4 Addition operator
• 7.7.5 Subtraction operator
• 7.8 Shift operators
• 7.9 Relational and type-testing operators
• 7.9.1 Integer comparison operators
• 7.9.2 Floating-point comparison operators
• 7.9.3 Decimal comparison operators
• 7.9.4 Boolean equality operators
• 7.9.5 Enumeration comparison operators
• 7.9.6 Reference type equality operators
• 7.9.7 String equality operators
• 7.9.8 Delegate equality operators
• 7.9.9 The is operator
• 7.9.10 The as operator
• 7.10 Logical operators
• 7.10.1 Integer logical operators
• 7.10.2 Enumeration logical operators
• 7.10.3 Boolean logical operators
• 7.11 Conditional logical operators
• 7.11.1 Boolean conditional logical operators
• 7.11.2 User-defined conditional logical operators
• 7.12 Conditional operator
• 7.13 Assignment operators
• 7.13.1 Simple assignment
• 7.13.2 Compound assignment
• 7.13.3 Event assignment
• 7.14 Expression
• 7.15 Constant expressions
• 7.16 Boolean expressions

• 8. Statements

• 8.1 End points and reachability
• 8.2 Blocks
• 8.2.1 Statement lists
• 8.3 The empty statement
• 8.4 Labeled statements
• 8.5 Declaration statements
• 8.5.1 Local variable declarations
• 8.5.2 Local constant declarations
• 8.6 Expression statements
• 8.7 Selection statements
• 8.7.1 The if statement
• 8.7.2 The switch statement
• 8.8 Iteration statements
• 8.8.1 The while statement
• 8.8.2 The do statement
• 8.8.3 The for statement
• 8.8.4 The foreach statement
• 8.9 Jump statements
• 8.9.1 The break statement
• 8.9.2 The continue statement
• 8.9.3 The goto statement
• 8.9.4 The return statement
• 8.9.5 The throw statement
• 8.10 The try statement
• 8.11 The checked and unchecked statements
• 8.12 The lock statement
• 8.13 The using statement

• 9. Namespaces

• 9.1 Compilation units
• 9.2 Namespace declarations
• 9.3 Using directives
• 9.3.1 Using alias directives
• 9.3.2 Using namespace directives
• 9.4 Namespace members
• 9.5 Type declarations

• 10. Classes

• 10.1 Class declarations
• 10.1.1 Class modifiers
• 10.1.1.1 Abstract classes
• 10.1.1.2 Sealed classes
• 10.1.2 Class base specification
• 10.1.2.1 Base classes
• 10.1.2.2 Interface implementations
• 10.1.3 Class body
• 10.2 Class members
• 10.2.1 Inheritance
• 10.2.2 The new modifier
• 10.2.3 Access modifiers
• 10.2.4 Constituent types
• 10.2.5 Static and instance members
• 10.2.6 Nested types
• 10.2.6.1 Fully qualified name
• 10.2.6.2 Declared accessibility
• 10.2.6.3 Hiding
• 10.2.6.4 this access
• 10.2.6.5 Access to private and protected members of the containing type
• 10.2.7 Reserved member names
• 10.2.7.1 Member names reserved for properties
• 10.2.7.2 Member names reserved for events
• 10.2.7.3 Member names reserved for indexers
• 10.2.7.4 Member names reserved for destructors
• 10.3 Constants
• 10.4 Fields
• 10.4.1 Static and instance fields
• 10.4.2 Readonly fields
• 10.4.2.1 Using static readonly fields for constants
• 10.4.2.2 Versioning of constants and static readonly fields
• 10.4.3 Volatile fields
• 10.4.4 Field initialization
• 10.4.5 Variable initializers
• 10.4.5.1 Static field initialization
• 10.4.5.2 Instance field initialization
• 10.5 Methods
• 10.5.1 Method parameters
• 10.5.1.1 Value parameters
• 10.5.1.2 Reference parameters
• 10.5.1.3 Output parameters
• 10.5.1.4 Parameter arrays
• 10.5.2 Static and instance methods
• 10.5.3 Virtual methods
• 10.5.4 Override methods
• 10.5.5 Sealed methods
• 10.5.6 Abstract methods
• 10.5.7 External methods
• 10.5.8 Method body
• 10.5.9 Method overloading
• 10.6 Properties
• 10.6.1 Static and instance properties
• 10.6.2 Accessors
• 10.6.3 Virtual, sealed, override, and abstract accessors
• 10.7 Events
• 10.7.1 Field-like events
• 10.7.2 Event accessors
• 10.7.3 Static and instance events
• 10.7.4 Virtual, sealed, override, and abstract accessors
• 10.8 Indexers
• 10.8.1 Indexer overloading
• 10.9 Operators
• 10.9.1 Unary operators
• 10.9.2 Binary operators
• 10.9.3 Conversion operators
• 10.10 Instance constructors
• 10.10.1 Constructor initializers
• 10.10.2 Instance variable initializers
• 10.10.3 Constructor execution
• 10.10.4 Default constructors
• 10.10.5 Private constructors
• 10.10.6 Optional instance constructor parameters
• 10.11 Static constructors
• 10.12 Destructors

• 11. Structs

• 11.1 Struct declarations
• 11.1.1 Struct modifiers
• 11.1.2 Struct interfaces
• 11.1.3 Struct body
• 11.2 Struct members
• 11.3 Class and struct differences
• 11.3.1 Value semantics
• 11.3.2 Inheritance
• 11.3.3 Assignment
• 11.3.4 Default values
• 11.3.5 Boxing and unboxing
• 11.3.6 Meaning of this
• 11.3.7 Field initializers
• 11.3.8 Constructors
• 11.3.9 Destructors
• 11.3.10 Static constructors
• 11.4 Struct examples
• 11.4.1 Database integer type
• 11.4.2 Database boolean type

• 12. Arrays

• 12.1 Array types
• 12.1.1 The System.Array type
• 12.2 Array creation
• 12.3 Array element access
• 12.4 Array members
• 12.5 Array covariance
• 12.6 Array initializers

• 13. Interfaces

• 13.1 Interface declarations
• 13.1.1 Interface modifiers
• 13.1.2 Base interfaces
• 13.1.3 Interface body
• 13.2 Interface members
• 13.2.1 Interface methods
• 13.2.2 Interface properties
• 13.2.3 Interface events
• 13.2.4 Interface indexers
• 13.2.5 Interface member access
• 13.3 Fully qualified interface member names
• 13.4 Interface implementations
• 13.4.1 Explicit interface member implementations
• 13.4.2 Interface mapping
• 13.4.3 Interface implementation inheritance
• 13.4.4 Interface re-implementation
• 13.4.5 Abstract classes and interfaces

• 14. Enums

• 14.1 Enum declarations
• 14.2 Enum modifiers
• 14.3 Enum members
• 14.4 The System.Enum type
• 14.5 Enum values and operations

• 15. Delegates

• 15.1 Delegate declarations
• 15.2 Delegate instantiation
• 15.3 Delegate invocation

• 16. Exceptions

• 16.1 Causes of exceptions
• 16.2 The System.Exception class
• 16.3 How exceptions are handled
• 16.4 Common Exception Classes

• 17. Attributes

• 17.1 Attribute classes
• 17.1.1 Attribute usage
• 17.1.2 Positional and named parameters
• 17.1.3 Attribute parameter types
• 17.2 Attribute specification
• 17.3 Attribute instances
• 17.3.1 Compilation of an attribute
• 17.3.2 Run-time retrieval of an attribute instance
• 17.4 Reserved attributes
• 17.4.1 The AttributeUsage attribute
• 17.4.2 The Conditional attribute
• 17.4.3 The Obsolete attribute
• 17.5 Attributes for Interoperation
• 17.5.1 Interoperation with COM and Win32 components
• 17.5.2 Interoperation with other .NET languages
• 17.5.2.1 The IndexerName attribute

• 18. Unsafe code

• 18.1 Unsafe contexts
• 18.2 Pointer types
• 18.3 Fixed and moveable variables
• 18.4 Pointer conversions
• 18.5 Pointers in expressions
• 18.5.1 Pointer indirection
• 18.5.2 Pointer member access
• 18.5.3 Pointer element access
• 18.5.4 The address-of operator
• 18.5.5 Pointer increment and decrement
• 18.5.6 Pointer arithmetic
• 18.5.7 Pointer comparison
• 18.5.8 The sizeof operator
• 18.6 The fixed statement
• 18.7 Stack allocation
• 18.8 Dynamic memory allocation

• A. Documentation comments

• A.1 Introduction
• A.2 Recommended tags
• A.2.1 <c>
• A.2.2 <code>
• A.2.3 <example>
• A.2.4 <exception>
• A.2.5 <include>
• A.2.6 <list>
• A.2.7 <para>
• A.2.8 <param>
• A.2.9 <paramref>
• A.2.10 <permission>
• A.2.11 <remarks>
• A.2.12 <returns>
• A.2.13 <see>
• A.2.14 <seealso>
• A.2.15 <summary>
• A.2.16 <value>
• A.3 Processing the documentation file
• A.3.1 ID string format
• A.3.2 ID string examples
• A.4 An example
• A.4.1 C# source code
• A.4.2 Resulting XML

• B. Grammar

• B.1 Lexical grammar
• B.1.1 Line terminators
• B.1.2 White space
• B.1.3 Comments
• B.1.4 Tokens
• B.1.5 Unicode character escape sequences
• B.1.6 Identifiers
• B.1.7 Keywords
• B.1.8 Literals
• B.1.9 Operators and punctuators
• B.1.10 Pre-processing directives
• B.2 Syntactic grammar
• B.2.1 Basic concepts
• B.2.2 Types
• B.2.3 Variables
• B.2.4 Expressions
• B.2.5 Statements
• B.2.6 Namespaces
• B.2.7 Classes
• B.2.8 Structs
• B.2.9 Arrays
• B.2.10 Interfaces
• B.2.11 Enums
• B.2.12 Delegates
• B.2.13 Attributes
• B.3 Grammar extensions for unsafe code

• C. References