Table of Contents 1 страницаLanguage Specification Version 4.0 Notice © 1999-2010 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 1.1 Hello world......................................................................................................................................... 1 1.2 Program structure............................................................................................................................... 2 1.3 Types and variables............................................................................................................................. 4 1.4 Expressions......................................................................................................................................... 6 1.5 Statements.......................................................................................................................................... 8 1.6 Classes and objects............................................................................................................................ 12 1.6.1 Members.................................................................................................................................... 12 1.6.2 Accessibility................................................................................................................................ 13 1.6.3 Type parameters......................................................................................................................... 13 1.6.4 Base classes............................................................................................................................... 14 1.6.5 Fields.......................................................................................................................................... 14 1.6.6 Methods..................................................................................................................................... 15 1.6.6.1 Parameters........................................................................................................................... 15 1.6.6.2 Method body and local variables............................................................................................. 16 1.6.6.3 Static and instance methods................................................................................................... 17 1.6.6.4 Virtual, override, and abstract methods................................................................................... 18 1.6.6.5 Method overloading............................................................................................................... 20 1.6.7 Other function members.............................................................................................................. 21 1.6.7.1 Constructors......................................................................................................................... 22 1.6.7.2 Properties............................................................................................................................. 23 1.6.7.3 Indexers............................................................................................................................... 23 1.6.7.4 Events.................................................................................................................................. 24 1.6.7.5 Operators............................................................................................................................. 24 1.6.7.6 Destructors........................................................................................................................... 25 1.7 Structs.............................................................................................................................................. 25 1.8 Arrays.............................................................................................................................................. 26 1.9 Interfaces......................................................................................................................................... 27 1.10 Enums............................................................................................................................................. 29 1.11 Delegates........................................................................................................................................ 30 1.12 Attributes........................................................................................................................................ 31 2. Lexical structure................................................................................................................................. 33 2.1 Programs.......................................................................................................................................... 33 2.2 Grammars......................................................................................................................................... 33 2.2.1 Grammar notation........................................................................................................................ 33 2.2.2 Lexical grammar......................................................................................................................... 34 2.2.3 Syntactic grammar...................................................................................................................... 34 2.3 Lexical analysis................................................................................................................................. 34 2.3.1 Line terminators.......................................................................................................................... 35 2.3.2 Comments.................................................................................................................................. 35 2.3.3 White space................................................................................................................................ 37 2.4 Tokens.............................................................................................................................................. 37 2.4.1 Unicode character escape sequences........................................................................................... 37 2.4.2 Identifiers................................................................................................................................... 38 2.4.3 Keywords................................................................................................................................... 39 2.4.4 Literals....................................................................................................................................... 40 2.4.4.1 Boolean literals...................................................................................................................... 40 2.4.4.2 Integer literals....................................................................................................................... 40 2.4.4.3 Real literals........................................................................................................................... 41 2.4.4.4 Character literals................................................................................................................... 42 2.4.4.5 String literals......................................................................................................................... 43 2.4.4.6 The null literal....................................................................................................................... 45 2.4.5 Operators and punctuators........................................................................................................... 45 2.5 Pre-processing directives................................................................................................................... 45 2.5.1 Conditional compilation symbols.................................................................................................... 47 2.5.2 Pre-processing expressions.......................................................................................................... 47 2.5.3 Declaration directives.................................................................................................................. 48 2.5.4 Conditional compilation directives................................................................................................. 49 2.5.5 Diagnostic directives.................................................................................................................... 51 2.5.6 Region directives......................................................................................................................... 52 2.5.7 Line directives............................................................................................................................. 52 2.5.8 Pragma directives........................................................................................................................ 53 2.5.8.1 Pragma warning.................................................................................................................... 53 3. Basic concepts.................................................................................................................................... 55 3.1 Application Startup............................................................................................................................ 55 3.2 Application termination....................................................................................................................... 56 3.3 Declarations...................................................................................................................................... 56 3.4 Members.......................................................................................................................................... 58 3.4.1 Namespace members.................................................................................................................. 58 3.4.2 Struct members........................................................................................................................... 59 3.4.3 Enumeration members................................................................................................................. 59 3.4.4 Class members............................................................................................................................ 59 3.4.5 Interface members...................................................................................................................... 60 3.4.6 Array members........................................................................................................................... 60 3.4.7 Delegate members...................................................................................................................... 60 3.5 Member access................................................................................................................................. 60 3.5.1 Declared accessibility.................................................................................................................. 60 3.5.2 Accessibility domains................................................................................................................... 61 3.5.3 Protected access for instance members........................................................................................ 63 3.5.4 Accessibility constraints............................................................................................................... 64 3.6 Signatures and overloading................................................................................................................. 65 3.7 Scopes.............................................................................................................................................. 66 3.7.1 Name hiding................................................................................................................................ 69 3.7.1.1 Hiding through nesting........................................................................................................... 69 3.7.1.2 Hiding through inheritance...................................................................................................... 70 3.8 Namespace and type names............................................................................................................... 71 3.8.1 Fully qualified names................................................................................................................... 73 3.9 Automatic memory management........................................................................................................ 73 3.10 Execution order............................................................................................................................... 76 4. Types................................................................................................................................................... 77 4.1 Value types....................................................................................................................................... 77 4.1.1 The System.ValueType type........................................................................................................ 78 4.1.2 Default constructors.................................................................................................................... 78 4.1.3 Struct types................................................................................................................................. 79 4.1.4 Simple types................................................................................................................................ 79 4.1.5 Integral types.............................................................................................................................. 80 4.1.6 Floating point types...................................................................................................................... 81 4.1.7 The decimal type......................................................................................................................... 82 4.1.8 The bool type.............................................................................................................................. 83 4.1.9 Enumeration types....................................................................................................................... 83 4.1.10 Nullable types............................................................................................................................ 83 4.2 Reference types................................................................................................................................ 83 4.2.1 Class types................................................................................................................................. 84 4.2.2 The object type........................................................................................................................... 85 4.2.3 The dynamic type........................................................................................................................ 85 4.2.4 The string type............................................................................................................................ 85 4.2.5 Interface types............................................................................................................................ 85 4.2.6 Array types................................................................................................................................. 85 4.2.7 Delegate types............................................................................................................................ 85 4.3 Boxing and unboxing.......................................................................................................................... 86 4.3.1 Boxing conversions...................................................................................................................... 86 4.3.2 Unboxing conversions.................................................................................................................. 87 4.4 Constructed types.............................................................................................................................. 88 4.4.1 Type arguments.......................................................................................................................... 89 4.4.2 Open and closed types................................................................................................................. 89 4.4.3 Bound and unbound types............................................................................................................ 89 4.4.4 Satisfying constraints................................................................................................................... 89 4.5 Type parameters............................................................................................................................... 90 4.6 Expression tree types......................................................................................................................... 91 4.7 The dynamic type.............................................................................................................................. 92 5. Variables............................................................................................................................................. 93 5.1 Variable categories............................................................................................................................ 93 5.1.1 Static variables............................................................................................................................ 93 5.1.2 Instance variables........................................................................................................................ 93 5.1.2.1 Instance variables in classes................................................................................................... 93 5.1.2.2 Instance variables in structs................................................................................................... 94 5.1.3 Array elements........................................................................................................................... 94 5.1.4 Value parameters........................................................................................................................ 94 5.1.5 Reference parameters................................................................................................................. 94 5.1.6 Output parameters....................................................................................................................... 94 5.1.7 Local variables............................................................................................................................ 95 5.2 Default values................................................................................................................................... 96 5.3 Definite assignment........................................................................................................................... 96 5.3.1 Initially assigned variables............................................................................................................ 97 5.3.2 Initially unassigned variables......................................................................................................... 97 5.3.3 Precise rules for determining definite assignment........................................................................... 97 5.3.3.1 General rules for statements................................................................................................... 98 5.3.3.2 Block statements, checked, and unchecked statements............................................................ 98 5.3.3.3 Expression statements........................................................................................................... 98 5.3.3.4 Declaration statements.......................................................................................................... 98 5.3.3.5 If statements......................................................................................................................... 98 5.3.3.6 Switch statements................................................................................................................. 99 5.3.3.7 While statements................................................................................................................... 99 5.3.3.8 Do statements....................................................................................................................... 99 5.3.3.9 For statements..................................................................................................................... 100 5.3.3.10 Break, continue, and goto statements................................................................................... 100 5.3.3.11 Throw statements.............................................................................................................. 100 5.3.3.12 Return statements.............................................................................................................. 100 5.3.3.13 Try-catch statements......................................................................................................... 100 5.3.3.14 Try-finally statements......................................................................................................... 101 5.3.3.15 Try-catch-finally statements............................................................................................... 101 5.3.3.16 Foreach statements............................................................................................................ 102 5.3.3.17 Using statements............................................................................................................... 102 5.3.3.18 Lock statements................................................................................................................ 102 5.3.3.19 Yield statements................................................................................................................ 103 5.3.3.20 General rules for simple expressions.................................................................................... 103 5.3.3.21 General rules for expressions with embedded expressions..................................................... 103 5.3.3.22 Invocation expressions and object creation expressions......................................................... 103 5.3.3.23 Simple assignment expressions............................................................................................ 104 5.3.3.24 && expressions................................................................................................................. 104 5.3.3.25 || expressions..................................................................................................................... 105 5.3.3.26! expressions..................................................................................................................... 106 5.3.3.27?? expressions................................................................................................................... 106 5.3.3.28?: expressions.................................................................................................................... 106 5.3.3.29 Anonymous functions......................................................................................................... 107 5.4 Variable references......................................................................................................................... 107 5.5 Atomicity of variable references....................................................................................................... 107 6. Conversions...................................................................................................................................... 109 6.1 Implicit conversions.......................................................................................................................... 109 6.1.1 Identity conversion..................................................................................................................... 109 6.1.2 Implicit numeric conversions....................................................................................................... 110 6.1.3 Implicit enumeration conversions................................................................................................ 110 6.1.4 Implicit nullable conversions....................................................................................................... 110 6.1.5 Null literal conversions............................................................................................................... 111 6.1.6 Implicit reference conversions.................................................................................................... 111 6.1.7 Boxing conversions.................................................................................................................... 111 6.1.8 Implicit dynamic conversions...................................................................................................... 112 6.1.9 Implicit constant expression conversions...................................................................................... 112 6.1.10 Implicit conversions involving type parameters........................................................................... 112 6.1.11 User-defined implicit conversions.............................................................................................. 113 6.1.12 Anonymous function conversions and method group conversions................................................. 113 6.2 Explicit conversions.......................................................................................................................... 113 6.2.1 Explicit numeric conversions....................................................................................................... 114 6.2.2 Explicit enumeration conversions................................................................................................ 115 6.2.3 Explicit nullable conversions....................................................................................................... 115 6.2.4 Explicit reference conversions.................................................................................................... 116 6.2.5 Unboxing conversions................................................................................................................ 117 6.2.6 Explicit dynamic conversions...................................................................................................... 117 6.2.7 Explicit conversions involving type parameters............................................................................. 118 6.2.8 User-defined explicit conversions................................................................................................ 119 6.3 Standard conversions....................................................................................................................... 119 6.3.1 Standard implicit conversions...................................................................................................... 119
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