x0005 c language referenc morebook vn 6573

C# Language Reference

Owners:

Anders Hejlsberg and Scott Wiltamuth

File:

C# Language Reference.doc

Last saved:

6/12/2000

Last printed: 6/26/2000
Version

0.17b

Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.


Notice
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Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.


Table of Contents

Table of Contents
1. Introduction........................................................................................................................................... 1
1.1 Hello, world ........................................................................................................................................1
1.2 Automatic memory management ..........................................................................................................2
1.3 Types..................................................................................................................................................4
1.4 Predefined types ..................................................................................................................................5
1.5 Array types .........................................................................................................................................7
1.6 Type system unification .......................................................................................................................9
1.7 Statements ........................................................................................................................................10
1.7.1 Statement lists and blocks ............................................................................................................10
1.7.2 Labeled statements and goto statements ......................................................................................10
1.7.3 Local declarations of constants and variables.................................................................................11
1.7.4 Expression statements..................................................................................................................11
1.7.5 The if statement ..........................................................................................................................11
1.7.6 The switch statement ...................................................................................................................12

1.7.7 The while statement ....................................................................................................................12
1.7.8 The do statement.........................................................................................................................13
1.7.9 The for statement ........................................................................................................................13
1.7.10 The foreach statement.............................................................................................................13
1.7.11 The break statement and the continue statement .....................................................................14
1.7.12 The return statement...............................................................................................................14
1.7.13 The throw statement.................................................................................................................14
1.7.14 The try statement.....................................................................................................................14
1.7.15 The checked and unchecked statements ..................................................................................14
1.7.16 The lock statement...................................................................................................................14
1.8 Classes .............................................................................................................................................14
1.9 Structs ..............................................................................................................................................15
1.10 Interfaces ........................................................................................................................................15
1.11 Delegates ........................................................................................................................................17
1.12 Enums .............................................................................................................................................18
1.13 Namespaces ....................................................................................................................................18
1.14 Properties........................................................................................................................................19
1.15 Indexers ..........................................................................................................................................20
1.16 Events.............................................................................................................................................21
1.17 Versioning.......................................................................................................................................22
1.18 Attributes ........................................................................................................................................24
2. Lexical structure .................................................................................................................................. 27
2.1 Phases of translation...........................................................................................................................27
2.2 Grammar notation..............................................................................................................................27
2.3 Pre-processing ...................................................................................................................................28
2.3.1 Pre-processing declarations ..........................................................................................................28
2.3.2 #if, #elif, #else, #endif .................................................................................................................29
2.3.3 Pre-processing control lines .........................................................................................................30
2.3.4 #line ...........................................................................................................................................31
2.3.5 Pre-processing identifiers.............................................................................................................31

2.3.6 Pre-processing expressions...........................................................................................................31
2.3.7 Interaction with white space.........................................................................................................32
2.4 Lexical analysis .................................................................................................................................33
2.4.1 Input...........................................................................................................................................33
Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

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C# LANGUAGE REFERENCE

2.4.2 Input characters...........................................................................................................................33
2.4.3 Line terminators ..........................................................................................................................33
2.4.4 Comments...................................................................................................................................33
2.4.5 White space ................................................................................................................................33
2.4.6 Tokens........................................................................................................................................33
2.5 Processing of Unicode character escape sequences ..............................................................................34
2.5.1 Identifiers ...................................................................................................................................34
2.5.2 Keywords ...................................................................................................................................36
2.5.3 Literals .......................................................................................................................................36
2.5.3.1 Boolean literals .....................................................................................................................36
2.5.3.2 Integer literals .......................................................................................................................36
2.5.3.3 Real literals ...........................................................................................................................37
2.5.3.4 Character literals ...................................................................................................................38
2.5.3.5 String literals.........................................................................................................................39
2.5.3.6 The null literal.......................................................................................................................40
2.5.4 Operators and punctuators............................................................................................................40
3. Basic concepts ...................................................................................................................................... 41
3.1 Declarations ......................................................................................................................................41
3.2 Members...........................................................................................................................................43

3.2.1 Namespace members...................................................................................................................43
3.2.2 Struct members ...........................................................................................................................43
3.2.3 Enumeration members .................................................................................................................44
3.2.4 Class members............................................................................................................................44
3.2.5 Interface members.......................................................................................................................44
3.2.6 Array members ...........................................................................................................................44
3.2.7 Delegate members.......................................................................................................................44
3.3 Member access..................................................................................................................................44
3.3.1 Declared accessibility ..................................................................................................................44
3.3.2 Accessibility domains ..................................................................................................................45
3.3.3 Protected access..........................................................................................................................47
3.3.4 Accessibility constraints...............................................................................................................48
3.4 Signatures and overloading.................................................................................................................49
3.5 Scopes ..............................................................................................................................................50
3.5.1 Name hiding................................................................................................................................52
3.5.1.1 Hiding through nesting...........................................................................................................52
3.5.1.2 Hiding through inheritance.....................................................................................................53
3.6 Namespace and type names................................................................................................................54
3.6.1 Fully qualified names ..................................................................................................................55
4. Types ................................................................................................................................................... 57
4.1 Value types .......................................................................................................................................57
4.1.1 Default constructors ....................................................................................................................58
4.1.2 Struct types.................................................................................................................................59
4.1.3 Simple types ...............................................................................................................................59
4.1.4 Integral types ..............................................................................................................................60
4.1.5 Floating point types .....................................................................................................................61
4.1.6 The decimal type .........................................................................................................................62
4.1.7 The bool type ............................................................................................................................63
4.1.8 Enumeration types.......................................................................................................................63
4.2 Reference types.................................................................................................................................63

iv

Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.


Table of Contents

4.2.1 Class types..................................................................................................................................64
4.2.2 The object type............................................................................................................................64
4.2.3 The string type ............................................................................................................................64
4.2.4 Interface types ............................................................................................................................64
4.2.5 Array types.................................................................................................................................64
4.2.6 Delegate types ............................................................................................................................64
4.3 Boxing and unboxing .........................................................................................................................65
4.3.1 Boxing conversions .....................................................................................................................65
4.3.2 Unboxing conversions .................................................................................................................66
5. Variables ............................................................................................................................................. 67
5.1 Variable categories ............................................................................................................................67
5.1.1 Static variables............................................................................................................................67
5.1.2 Instance variables ........................................................................................................................67
5.1.2.1 Instance variables in classes...................................................................................................67
5.1.2.2 Instance variables in structs....................................................................................................68
5.1.3 Array elements............................................................................................................................68
5.1.4 Value parameters ........................................................................................................................68
5.1.5 Reference parameters ..................................................................................................................68
5.1.6 Output parameters.......................................................................................................................68
5.1.7 Local variables............................................................................................................................69
5.2 Default values ...................................................................................................................................69
5.3 Definite assignment ...........................................................................................................................69

5.3.1 Initially assigned variables ...........................................................................................................72
5.3.2 Initially unassigned variables .......................................................................................................72
5.4 Variable references ............................................................................................................................72
6. Conversions ......................................................................................................................................... 73
6.1 Implicit conversions...........................................................................................................................73
6.1.1 Identity conversion......................................................................................................................73
6.1.2 Implicit numeric conversions........................................................................................................73
6.1.3 Implicit enumeration conversions .................................................................................................74
6.1.4 Implicit reference conversions ......................................................................................................74
6.1.5 Boxing conversions .....................................................................................................................74
6.1.6 Implicit constant expression conversions.......................................................................................74
6.1.7 User-defined implicit conversions.................................................................................................75
6.2 Explicit conversions...........................................................................................................................75
6.2.1 Explicit numeric conversions........................................................................................................75
6.2.2 Explicit enumeration conversions .................................................................................................76
6.2.3 Explicit reference conversions ......................................................................................................76
6.2.4 Unboxing conversions .................................................................................................................77
6.2.5 User-defined explicit conversions .................................................................................................77
6.3 Standard conversions .........................................................................................................................77
6.3.1 Standard implicit conversions.......................................................................................................77
6.3.2 Standard explicit conversions .......................................................................................................78
6.4 User-defined conversions ...................................................................................................................78
6.4.1 Permitted user-defined conversions...............................................................................................78
6.4.2 Evaluation of user-defined conversions .........................................................................................78
6.4.3 User-defined implicit conversions.................................................................................................79
6.4.4 User-defined explicit conversions .................................................................................................80
7. Expressions .......................................................................................................................................... 81
Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

v

Chapter 21 References

21. References
Unicode Consortium. The Unicode Standard, Version 3.0. Addison-Wesley, Reading, Massachusetts, 2000,
ISBN 0-201-616335-5.
IEEEE. IEEE Standard for Binary Floating-Point Arithmetic. ANSI/IEEE Standard 754-1985. Available from
.
ISO/IEC. C++. ANSI/ISO/IEC 14882:1998.

Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

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