ISO IEC 23270-2006 Information technology - Programming languages - C Sharp《信息技术 程序语言 C Sharp》.pdf

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1、 Reference number ISO/IEC 23270:2006(E) ISO/IEC 2006INTERNATIONAL STANDARD ISO/IEC 23270 Second edition 2006-09-01 Information technology Programming languages C# Technologies de linformation Langages de programmation C# ISO/IEC 23270:2006(E) PDF disclaimer This PDF file may contain embedded typefac

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4、ed for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO/IEC 2006 All rights reserved. Unless otherwise specified, n

5、o part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case post

6、ale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2006 All rights reservedISO/IEC 23270:2006(E) ISO/IEC 2006 All rights reserved iii Table of Contents Foreword xv Introduction xvi 1. Scope . 1 2. Conforma

7、nce . 3 3. Normative references 5 4. Terms and definitions 7 5. Notational conventions 9 6. Acronyms and abbreviations . 11 7. General description. 13 8. Language overview 15 8.1 Getting started . 15 8.2 Types. 16 8.2.1 Predefined types. 17 8.2.2 Conversions 19 8.2.3 Array types. 20 8.2.4 Type syste

8、m unification . 22 8.3 Variables and parameters 22 8.4 Automatic memory management 25 8.5 Expressions . 27 8.6 Statements . 28 8.7 Classes. 31 8.7.1 Constants 33 8.7.2 Fields 33 8.7.3 Methods 34 8.7.4 Properties . 35 8.7.5 Events. 36 8.7.6 Operators 37 8.7.7 Indexers 38 8.7.8 Instance constructors 3

9、9 8.7.9 Finalizers 40 8.7.10 Static constructors 40 8.7.11 Inheritance 41 8.7.12 Static classes 42 8.7.13 Partial type declarations . 42 8.8 Structs 43 8.9 Interfaces . 44 8.10 Delegates . 45 8.11 Enums 46 8.12 Namespaces and assemblies 46 8.13 Versioning . 48 8.14 Extern aliases. 49 8.15 Attributes

10、. 51 8.16 Generics. 52 ISO/IEC 23270:2006(E) i v ISO/IEC 2006 All rights reserved 8.16.1 Why generics? 52 8.16.2 Creating and consuming generics 53 8.16.3 Multiple type parameters 54 8.16.4 Constraints . 54 8.16.5 Generic methods 56 8.17 Anonymous methods. 56 8.18 Iterators . 59 8.19 Nullable types

11、62 9. Lexical structure 65 9.1 Programs . 65 9.2 Grammars 65 9.2.1 Lexical grammar 65 9.2.2 Syntactic grammar . 65 9.2.3 Grammar ambiguities. 66 9.3 Lexical analysis. 66 9.3.1 Line terminators . 67 9.3.2 Comments 67 9.3.3 White space 69 9.4 Tokens. 69 9.4.1 Unicode escape sequences . 69 9.4.2 Identi

12、fiers . 70 9.4.3 Keywords . 71 9.4.4 Literals . 72 9.4.4.1 Boolean literals 72 9.4.4.2 Integer literals 72 9.4.4.3 Real literals 73 9.4.4.4 Character literals . 74 9.4.4.5 String literals . 75 9.4.4.6 The null literal. 76 9.4.5 Operators and punctuators 77 9.5 Pre-processing directives. 77 9.5.1 Con

13、ditional compilation symbols 78 9.5.2 Pre-processing expressions 78 9.5.3 Declaration directives. 79 9.5.4 Conditional compilation directives 80 9.5.5 Diagnostic directives 82 9.5.6 Region control 83 9.5.7 Line directives 83 9.5.8 Pragma directives. 84 10. Basic concepts 85 10.1 Application startup

14、85 10.2 Application termination. 86 10.3 Declarations. 86 10.4 Members 89 10.4.1 Namespace members 89 10.4.2 Struct members 89 10.4.3 Enumeration members . 89 10.4.4 Class members . 89 10.4.5 Interface members 90 10.4.6 Array members. 90 10.4.7 Delegate members 90 10.5 Member access 90 10.5.1 Declar

15、ed accessibility. 90 ISO/IEC 23270:2006(E) ISO/IEC 2006 All rights reserved v 10.5.2 Accessibility domains 91 10.5.3 Protected access for instance members 93 10.5.4 Accessibility constraints. 94 10.6 Signatures and overloading . 95 10.7 Scopes . 96 10.7.1 Name hiding. 98 10.7.1.1 Hiding through nest

16、ing 98 10.7.1.2 Hiding through inheritance 99 10.8 Namespace and type names. 100 10.8.1 Unqualified name. 102 10.8.2 Fully qualified names. 102 10.9 Automatic memory management 103 10.10 Execution order . 105 11. Types 107 11.1 Value types 107 11.1.1 The System.ValueType type 108 11.1.2 Default cons

17、tructors . 108 11.1.3 Struct types. 109 11.1.4 Simple types. 109 11.1.5 Integral types 110 11.1.6 Floating point types 111 11.1.7 The decimal type 111 11.1.8 The bool type . 112 11.1.9 Enumeration types 112 11.2 Reference types . 112 11.2.1 Class types 113 11.2.2 The object type. 113 11.2.3 The stri

18、ng type . 113 11.2.4 Interface types 113 11.2.5 Array types. 114 11.2.6 Delegate types 114 11.2.7 The null type 114 11.3 Boxing and unboxing 114 11.3.1 Boxing conversions 114 11.3.2 Unboxing conversions 115 11.4 Nullable types 116 11.4.1 Members. 116 11.4.2 Implemented interfaces 117 12. Variables 1

19、19 12.1 Variable categories 119 12.1.1 Static variables . 119 12.1.2 Instance variables. 119 12.1.2.1 Instance variables in classes 119 12.1.2.2 Instance variables in structs. 120 12.1.3 Array elements . 120 12.1.4 Value parameters 120 12.1.5 Reference parameters. 120 12.1.6 Output parameters 120 12

20、.1.7 Local variables . 121 12.2 Default values 121 12.3 Definite assignment. 122 12.3.1 Initially assigned variables. 123 12.3.2 Initially unassigned variables. 123 ISO/IEC 23270:2006(E) v i ISO/IEC 2006 All rights reserved 12.3.3 Precise rules for determining definite assignment . 123 12.3.3.1 Gene

21、ral rules for statements 124 12.3.3.2 Block statements, checked, and unchecked statements. 124 12.3.3.3 Expression statements . 124 12.3.3.4 Declaration statements 124 12.3.3.5 If statements 124 12.3.3.6 Switch statements 125 12.3.3.7 While statements . 125 12.3.3.8 Do statements 125 12.3.3.9 For st

22、atements . 125 12.3.3.10 Break, continue, and goto statements 126 12.3.3.11 Throw statements 126 12.3.3.12 Return statements 126 12.3.3.13 Try-catch statements . 126 12.3.3.14 Try-finally statements . 127 12.3.3.15 Try-catch-finally statements 127 12.3.3.16 Foreach statements 128 12.3.3.17 Using sta

23、tements . 128 12.3.3.18 Lock statements. 128 12.3.3.19 General rules for simple expressions 128 12.3.3.20 General rules for expressions with embedded expressions . 129 12.3.3.21 Invocation expressions and object creation expressions . 129 12.3.3.22 Simple assignment expressions. 129 12.3.3.23 & expr

24、essions. 130 12.3.3.24 | expressions 131 12.3.3.25 ! expressions 131 12.3.3.26 ?: expressions 132 12.3.3.27 Anonymous method expressions. 132 12.3.3.28 Yield statements 133 12.3.3.29 ? expressions 133 12.4 Variable references 133 12.5 Atomicity of variable references . 133 13. Conversions 135 13.1 I

25、mplicit conversions 135 13.1.1 Identity conversion. 135 13.1.2 Implicit numeric conversions. 135 13.1.3 Implicit enumeration conversions 136 13.1.4 Implicit reference conversions . 136 13.1.5 Boxing conversions 137 13.1.6 Implicit type parameter conversions 137 13.1.7 Implicit constant expression co

26、nversions. 138 13.1.8 User-defined implicit conversions . 138 13.2 Explicit conversions 138 13.2.1 Explicit numeric conversions. 138 13.2.2 Explicit enumeration conversions 140 13.2.3 Explicit reference conversions . 140 13.2.4 Unboxing conversions 141 13.2.5 Explicit type parameter conversions 141

27、13.2.6 User-defined explicit conversions 142 13.3 Standard conversions. 142 13.3.1 Standard implicit conversions 142 13.3.2 Standard explicit conversions 142 13.4 User-defined conversions 142 13.4.1 Permitted user-defined conversions . 142 ISO/IEC 23270:2006(E) ISO/IEC 2006 All rights reserved v i i

28、 13.4.2 Evaluation of user-defined conversions . 143 13.4.3 User-defined implicit conversions . 144 13.4.4 User-defined explicit conversions 144 13.5 Anonymous method conversions 145 13.6 Method group conversions 146 13.7 Conversions involving nullable types . 147 13.7.1 Null type conversions. 148 1

29、3.7.2 Nullable conversions 148 13.7.3 Lifted conversions 148 14. Expressions 149 14.1 Expression classifications . 149 14.1.1 Values of expressions. 150 14.2 Operators . 150 14.2.1 Operator precedence and associativity. 150 14.2.2 Operator overloading . 151 14.2.3 Unary operator overload resolution

30、. 152 14.2.4 Binary operator overload resolution. 153 14.2.5 Candidate user-defined operators. 153 14.2.6 Numeric promotions. 153 14.2.6.1 Unary numeric promotions 154 14.2.6.2 Binary numeric promotions. 154 14.2.7 Lifted operators 155 14.3 Member lookup . 156 14.3.1 Base types 157 14.4 Function mem

31、bers. 157 14.4.1 Argument lists 159 14.4.2 Overload resolution 161 14.4.2.1 Applicable function member. 162 14.4.2.2 Better function member. 163 14.4.2.3 Better conversion 163 14.4.3 Function member invocation 164 14.4.3.1 Invocations on boxed instances. 165 14.5 Primary expressions 165 14.5.1 Liter

32、als . 166 14.5.2 Simple names . 166 14.5.2.1 Invariant meaning in blocks 168 14.5.3 Parenthesized expressions 168 14.5.4 Member access. 169 14.5.4.1 Identical simple names and type names 170 14.5.5 Invocation expressions. 171 14.5.5.1 Method invocations. 171 14.5.5.2 Delegate invocations . 172 14.5.

33、6 Element access . 173 14.5.6.1 Array access 173 14.5.6.2 Indexer access . 173 14.5.7 This access . 174 14.5.8 Base access. 175 14.5.9 Postfix increment and decrement operators . 175 14.5.10 The new operator 176 14.5.10.1 Object creation expressions. 176 14.5.10.2 Array creation expressions 178 14.5

34、.10.3 Delegate creation expressions . 179 14.5.11 The typeof operator 182 14.5.12 The sizeof operator. 184 ISO/IEC 23270:2006(E) viii ISO/IEC 2006 All rights reserved 14.5.13 The checked and unchecked operators. 184 14.5.14 Default value expression 187 14.5.15 Anonymous methods 187 14.5.15.1 Anonymo

35、us method signatures . 187 14.5.15.2 Anonymous method blocks. 188 14.5.15.3 Outer variables 188 14.5.15.4 Anonymous method evaluation. 191 14.5.15.5 Implementation example. 191 14.6 Unary expressions . 194 14.6.1 Unary plus operator 194 14.6.2 Unary minus operator. 194 14.6.3 Logical negation operat

36、or 195 14.6.4 Bitwise complement operator 195 14.6.5 Prefix increment and decrement operators. 195 14.6.6 Cast expressions. 196 14.7 Arithmetic operators 197 14.7.1 Multiplication operator. 197 14.7.2 Division operator 198 14.7.3 Remainder operator 199 14.7.4 Addition operator . 200 14.7.5 Subtracti

37、on operator. 202 14.8 Shift operators . 204 14.9 Relational and type-testing operators 205 14.9.1 Integer comparison operators. 206 14.9.2 Floating-point comparison operators . 207 14.9.3 Decimal comparison operators. 207 14.9.4 Boolean equality operators. 208 14.9.5 Enumeration comparison operators

38、 208 14.9.6 Reference type equality operators 208 14.9.7 String equality operators 210 14.9.8 Delegate equality operators 210 14.9.9 Equality operators and null 211 14.9.10 is operator. 211 14.9.11 as operator 212 14.10 Logical operators. 213 14.10.1 Integer logical operators. 213 14.10.2 Enumeratio

39、n logical operators . 214 14.10.3 Boolean logical operators. 214 14.10.4 The bool? logical operators 214 14.11 Conditional logical operators 215 14.11.1 Boolean conditional logical operators 215 14.11.2 User-defined conditional logical operators 216 14.12 The null coalescing operator . 216 14.13 Con

40、ditional operator 217 14.14 Assignment operators 218 14.14.1 Simple assignment . 218 14.14.2 Compound assignment. 220 14.14.3 Event assignment . 221 14.15 Expression . 221 14.16 Constant expressions. 221 14.17 Boolean expressions 222 15. Statements 225 15.1 End points and reachability . 225 15.2 Blo

41、cks 227 ISO/IEC 23270:2006(E) ISO/IEC 2006 All rights reserved i x 15.2.1 Statement lists 227 15.3 The empty statement . 227 15.4 Labeled statements 228 15.5 Declaration statements 228 15.5.1 Local variable declarations 229 15.5.2 Local constant declarations 229 15.6 Expression statements . 230 15.7

42、 Selection statements 230 15.7.1 The if statement 230 15.7.2 The switch statement 231 15.8 Iteration statements . 234 15.8.1 The while statement . 234 15.8.2 The do statement 235 15.8.3 The for statement . 235 15.8.4 The foreach statement 236 15.9 Jump statements 239 15.9.1 The break statement . 240

43、 15.9.2 The continue statement 241 15.9.3 The goto statement . 241 15.9.4 The return statement. 242 15.9.5 The throw statement. 243 15.10 The try statement. 244 15.11 The checked and unchecked statements 246 15.12 The lock statement 247 15.13 The using statement. 247 15.14 The yield statement . 249

44、16. Namespaces 251 16.1 Compilation units 251 16.2 Namespace declarations 251 16.3 Extern alias directives . 252 16.4 Using directives. 253 16.4.1 Using alias directives . 253 16.4.2 Using namespace directives . 257 16.5 Namespace members. 259 16.6 Type declarations 259 16.7 Qualified alias member .

45、 259 17. Classes 263 17.1 Class declarations 263 17.1.1 Class modifiers. 263 17.1.1.1 Abstract classes . 264 17.1.1.2 Sealed classes 264 17.1.1.3 Static classes 264 17.1.2 Class base specification 265 17.1.2.1 Base classes. 266 17.1.2.2 Interface implementations. 267 17.1.3 Class body 268 17.1.4 Par

46、tial declarations. 268 17.2 Class members. 269 17.2.1 Inheritance 271 17.2.2 The new modifier . 272 17.2.3 Access modifiers 272 17.2.4 Constituent types 272 17.2.5 Static and instance members 272 ISO/IEC 23270:2006(E) x ISO/IEC 2006 All rights reserved 17.2.6 Nested types . 273 17.2.6.1 Fully qualif

47、ied name . 273 17.2.6.2 Declared accessibility 274 17.2.6.3 Hiding 274 17.2.6.4 this access 275 17.2.6.5 Access to private and protected members of the containing type . 275 17.2.7 Reserved member names 276 17.2.7.1 Member names reserved for properties. 276 17.2.7.2 Member names reserved for events.

48、 277 17.2.7.3 Member names reserved for indexers . 277 17.2.7.4 Member names reserved for finalizers 277 17.3 Constants . 277 17.4 Fields. 279 17.4.1 Static and instance fields 280 17.4.2 Readonly fields 280 17.4.2.1 Using static readonly fields for constants 281 17.4.2.2 Versioning of constants and

49、 static readonly fields 281 17.4.3 Volatile fields. 282 17.4.4 Field initialization 283 17.4.5 Variable initializers 283 17.4.5.1 Static field initialization 284 17.4.5.2 Instance field initialization 285 17.5 Methods. 285 17.5.1 Method parameters. 287 17.5.1.1 Value parameters. 288 17.5.1.2 Reference parameters 288 17.5.1.3 Output parameters . 289 17.5.1.4 Parameter arrays 290 17.5.2 Static and instance methods . 292 17.5.3 Virtual methods 292 17.5.4 Override methods. 294 17.5.5 Sealed methods 296 17.5.6 Abstrac