C#语言参考-优快云博客

C#语言参考

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Table of Contents

1. 介绍....................................................................................................................................................................1

1.1 Hello, world..................................................................................................................................................1

1.2 类型..............................................................................................................................................................2

1.2.1 预定义类型...........................................................................................................................................3

1.2.2 转换.......................................................................................................................................................5

1.2.3 数组类型...............................................................................................................................................6

1.2.4 类型系统一致.......................................................................................................................................7

1.3 变量和参数..................................................................................................................................................8

1.4 自动内存管理............................................................................................................................................11

1.5 表达式........................................................................................................................................................13

1.6 声明............................................................................................................................................................15

1.7 类................................................................................................................................................................18

1.7.1 常数.....................................................................................................................................................20

1.7.2 域.........................................................................................................................................................20

1.7.3 方法.....................................................................................................................................................21

1.7.4 属性.....................................................................................................................................................22

1.7.5 事件.....................................................................................................................................................23

1.7.6 操作符.................................................................................................................................................24

1.7.7 索引.....................................................................................................................................................25

1.7.8 实例构造函数.....................................................................................................................................26

1.7.9 析构函数.............................................................................................................................................27

1.7.10 静态构造函数...................................................................................................................................27

1.7.11 继承...................................................................................................................................................28

1.8 结构............................................................................................................................................................29

1.9 接口............................................................................................................................................................30

1.10 代表..........................................................................................................................................................31

1.11 联合..........................................................................................................................................................32

1.12 名称空间和集合......................................................................................................................................32

1.13 版本..........................................................................................................................................................34

1.14 特征..........................................................................................................................................................36

2. 语法结构..........................................................................................................................................................39

2.1 翻译的阶段................................................................................................................................................39

2.2 文法符号....................................................................................................................................................39

2.3 预处理........................................................................................................................................................40

2.3.1 预处理声明.........................................................................................................................................40

2.3.2 #if, #elif, #else, #endif..........................................................................................................................41

2.3.3 预处理控制行.....................................................................................................................................42

2.3.4 #line.....................................................................................................................................................43

2.3.5 预处理标识符.....................................................................................................................................43

2.3.6 预处理表达式.....................................................................................................................................43

2.3.7 与空白交互作用.................................................................................................................................44

2.4 语法分析....................................................................................................................................................45 Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved. iii

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2.4.1 输入.....................................................................................................................................................45

2.4.2 输入字符.............................................................................................................................................45

2.4.3 行结束符.............................................................................................................................................45

2.4.4 注释.....................................................................................................................................................45

2.4.5 空白.....................................................................................................................................................46

2.4.6 标记.....................................................................................................................................................47

2.5 句法分析....................................................................................................................................................47

2.5.1 标识符.................................................................................................................................................47

2.5.2 关键字.................................................................................................................................................48

2.5.3 数据符号.............................................................................................................................................48

2.5.4 操作符和标点.....................................................................................................................................53

2.5.5 Unicode 字符转意字符序列................................................................................................................53

3. 基本概念..........................................................................................................................................................55

3.1 声明............................................................................................................................................................55

3.2 成员............................................................................................................................................................57

3.2.1 名称空间成员.....................................................................................................................................57

3.2.2 结构成员.............................................................................................................................................57

3.2.3 枚举成员.............................................................................................................................................57

3.2.4 类成员.................................................................................................................................................58

3.2.5 接口成员.............................................................................................................................................58

3.2.6 数组成员.............................................................................................................................................58

3.2.7 代表成员.............................................................................................................................................58

3.3 成员访问....................................................................................................................................................58

3.3.1 声明可访问性.....................................................................................................................................58

3.3.2 可访问性域.........................................................................................................................................59

3.3.3 保护的访问.........................................................................................................................................61

3.3.4 可访问性约束.....................................................................................................................................62

3.4 签名和重载................................................................................................................................................62

3.5 范围............................................................................................................................................................63

3.5.1 名称隐藏.............................................................................................................................................65

3.6 名称空间或类型名称................................................................................................................................67

3.6.1 合格的名称.........................................................................................................................................68

4. 类型..................................................................................................................................................................69

4.1 数值类型....................................................................................................................................................69

4.1.1 默认构造函数.....................................................................................................................................70

4.1.2 结构类型.............................................................................................................................................71

4.1.3 简单类型.............................................................................................................................................71

4.1.4 整数类型.............................................................................................................................................72

4.1.5 浮点类型.............................................................................................................................................73

4.1.6 十进制类型.........................................................................................................................................74

4.1.7 布尔类型...........................................................................................................................................74

4.1.8 枚举类型.............................................................................................................................................74

4.2 引用类型....................................................................................................................................................74

4.2.1 类类型.................................................................................................................................................75 iv Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

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4.2.2 对象类型.............................................................................................................................................75

4.2.3 字符串类型.........................................................................................................................................75

4.2.4 接口类型.............................................................................................................................................76

4.2.5 数组类型.............................................................................................................................................76

4.2.6 代表类型.............................................................................................................................................76

4.3 包装和解包................................................................................................................................................76

4.3.1 包装转换.............................................................................................................................................76

4.3.2 解包转换.............................................................................................................................................77

5. 变量..................................................................................................................................................................79

5.1 变量类型....................................................................................................................................................79

5.1.1 静态变量.............................................................................................................................................79

5.1.2 实例变量.............................................................................................................................................79

5.1.3 数组元素.............................................................................................................................................80

5.1.4 数值参数.............................................................................................................................................80

5.1.5 引用参数.............................................................................................................................................80

5.1.6 输出参数.............................................................................................................................................80

5.1.7 局部变量.............................................................................................................................................81

5.2 默认值........................................................................................................................................................81

5.3 明确赋值....................................................................................................................................................81

5.3.1 初始赋值变量.....................................................................................................................................83

5.3.2 非初始赋值变量.................................................................................................................................84

5.4 变量引用....................................................................................................................................................84

6. 转换..................................................................................................................................................................85

6.1 隐式转换....................................................................................................................................................85

6.1.1 同一性转换.........................................................................................................................................85

6.1.2 隐式数值转换.....................................................................................................................................85

6.1.3 隐式枚举转换.....................................................................................................................................86

6.1.4 隐式引用转换.....................................................................................................................................86

6.1.5 转换.....................................................................................................................................................86

6.1.6 隐式常数表达式转换..........................................................................................................................86

6.1.7 用户自定义隐式转换..........................................................................................................................87

6.2 显式转换....................................................................................................................................................87

6.2.1 显式数值转换.....................................................................................................................................87

6.2.2 显式枚举类型转换..............................................................................................................................88

6.2.3 显式引用类型转换..............................................................................................................................88

6.2.4 解包转换.............................................................................................................................................89

6.2.5 用户自定义显式转换..........................................................................................................................89

6.3 标准转换....................................................................................................................................................89

6.3.1 标准隐式转换.....................................................................................................................................89

6.3.2 标准显式转换.....................................................................................................................................90

6.4 用户定义转换............................................................................................................................................90

6.4.1 允许的用户自定义转换.......................................................................................................................90

6.4.2 用户自定义转换的取值.......................................................................................................................90

6.4.3 用户自定义隐式转换..........................................................................................................................91 Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved. v

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6.4.4 用户自定义显式类型转换...................................................................................................................91

7. 表达式..............................................................................................................................................................93

7.1 表达式分类................................................................................................................................................93

7.1.1 表达式的数值.....................................................................................................................................94

7.2 操作符........................................................................................................................................................94

7.2.1 操作符优先级和结合顺序...................................................................................................................94

7.2.2 操作符重载.........................................................................................................................................96

7.2.3 一元操作符重载分析..........................................................................................................................97

7.2.4 二元操作符重载分析..........................................................................................................................97

7.2.5 候选用户定义操作符..........................................................................................................................98

7.2.6 数字升级.............................................................................................................................................98

7.3 成员查询....................................................................................................................................................99

7.3.1 基类型...............................................................................................................................................100

7.4 函数成员..................................................................................................................................................100

7.4.1 参数列表...........................................................................................................................................102

7.4.2 重载分析...........................................................................................................................................103

7.4.3 功能成员调用...................................................................................................................................105

7.4.4 虚拟函数成员查找............................................................................................................................106

7.4.5 接口函数成员查找............................................................................................................................106

7.5 主要的表达式..........................................................................................................................................106

7.5.1 文字...................................................................................................................................................106

7.5.2 简单名称...........................................................................................................................................107

7.5.3 加括号的表达式...............................................................................................................................108

7.5.4 成员访问...........................................................................................................................................108

7.5.5 调用表达式.......................................................................................................................................110

7.5.6 元素访问...........................................................................................................................................112

7.5.7 This访问............................................................................................................................................113

7.5.8 基本访问...........................................................................................................................................114

7.5.9 递增和递减后缀操作符.....................................................................................................................114

7.5.10 new操作符......................................................................................................................................115

7.5.11 typeof操作符.............................................................................................................................119

7.5.12 sizeof操作符............................................................................................................................119

7.5.13 checked和unchecked操作符.................................................................................................120

7.6 一元表达式..............................................................................................................................................122

7.6.1 一元正值运算符...............................................................................................................................122

7.6.2 一元负值运算符...............................................................................................................................122

7.6.3 逻辑非运算符...................................................................................................................................123

7.6.4 按位求补运算符...............................................................................................................................123

7.6.5 间接运算符.......................................................................................................................................123

7.6.6 地址运算符.......................................................................................................................................123

7.6.7 前缀增量和减量运算符.....................................................................................................................123

7.6.8 强制类型转换表达式........................................................................................................................124

7.7 算术运算符..............................................................................................................................................125

7.7.1 乘法运算符.......................................................................................................................................125 vi Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

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7.7.2 除法运算符.......................................................................................................................................126

7.7.3 余数运算符.......................................................................................................................................127

7.7.4 加法运算符.......................................................................................................................................127

7.7.5 减法运算符.......................................................................................................................................129

7.8 移位运算符..............................................................................................................................................130

7.9 关系运算符..............................................................................................................................................131

7.9.1 整数比较运算符...............................................................................................................................132

7.9.2 浮点比较运算符...............................................................................................................................132

7.9.3 小数比较运算符...............................................................................................................................133

7.9.4 布尔相等运算符...............................................................................................................................133

7.9.5 枚举比较运算符...............................................................................................................................133

7.9.6 引用类型相等运算符........................................................................................................................133

7.9.7 字符串相等运算符............................................................................................................................135

7.9.8 代表相等运算符...............................................................................................................................135

7.9.9 is 运算符............................................................................................................................................135

7.10 逻辑运算符............................................................................................................................................136

7.10.1 整数逻辑运算符..............................................................................................................................136

7.10.2 枚举逻辑运算符..............................................................................................................................136

7.10.3 布尔逻辑运算符..............................................................................................................................137

7.11 条件逻辑运算符....................................................................................................................................137

7.11.1 布尔条件逻辑运算符.......................................................................................................................137

7.11.2 用户自定义的条件逻辑运算符.......................................................................................................138

7.12 条件运算符............................................................................................................................................138

7.13 赋值运算符............................................................................................................................................139

7.13.1 简单赋值.........................................................................................................................................139

7.13.2 组合赋值.........................................................................................................................................141

7.13.3 事件赋值.........................................................................................................................................142

7.14 表达式....................................................................................................................................................142

7.15 常量表达式............................................................................................................................................142

7.16 布尔表达式............................................................................................................................................143

8. 语句................................................................................................................................................................145

8.1 终点与可达性..........................................................................................................................................145

8.2 块 146

8.2.1 语句列表...........................................................................................................................................147

8.3 空语句......................................................................................................................................................147

8.4 标号语句..................................................................................................................................................148

8.5 声明语句..................................................................................................................................................148

8.5.1 局部变量声明...................................................................................................................................148

8.5.2 局部常量声明...................................................................................................................................149

8.6 表达式语句..............................................................................................................................................150

8.7 选择语句..................................................................................................................................................150

8.7.1 if语句................................................................................................................................................150

8.7.2 Switch 语句.......................................................................................................................................151

8.8 重复语句..................................................................................................................................................154 Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved. vii

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8.8.1 while语句..........................................................................................................................................155

8.8.2 do语句...............................................................................................................................................155

8.8.3 for语句..............................................................................................................................................155

8.8.4 foreach语句.......................................................................................................................................157

8.9 跳转语句..................................................................................................................................................158

8.9.1 break语句..........................................................................................................................................158

8.9.2 continue语句.....................................................................................................................................159

8.9.3 goto语句............................................................................................................................................159

8.9.4 return语句.........................................................................................................................................160

8.9.5 throw语句.........................................................................................................................................160

8.10 try语句...................................................................................................................................................161

8.11 checked和unchecked语句....................................................................................................................163

8.12 lock语句................................................................................................................................................163

9. 名称空间........................................................................................................................................................165

9.1 编译单元..................................................................................................................................................165

9.2 名称空间声明..........................................................................................................................................165

9.3 使用指示..................................................................................................................................................166

9.3.1 使用别名指示...................................................................................................................................167

9.3.2 使用名称空间指示............................................................................................................................169

9.4 名称空间成员..........................................................................................................................................170

9.5 类型声明..................................................................................................................................................171

10. 类..................................................................................................................................................................173

10.1 类声明....................................................................................................................................................173

10.1.1 类修饰符.........................................................................................................................................173

10.1.2 类基础规范.....................................................................................................................................174

10.1.3 类主体.............................................................................................................................................176

10.2 类成员....................................................................................................................................................176

10.2.1 继承.................................................................................................................................................177

10.2.2 new修饰符......................................................................................................................................177

10.2.3 访问修饰符.....................................................................................................................................178

10.2.4 要素类型.........................................................................................................................................178

10.2.5 静态和实例成员..............................................................................................................................178

10.2.6 嵌套类型.........................................................................................................................................179

10.3 常数........................................................................................................................................................179

10.4 域............................................................................................................................................................180

10.4.1 静态和实例域.................................................................................................................................181

10.4.2 只读域.............................................................................................................................................182

10.4.3 域的初始化.....................................................................................................................................183

10.4.4 变量初始化函数..............................................................................................................................183

10.5 方法........................................................................................................................................................185

10.5.1 方法参数.........................................................................................................................................186

10.5.2 静态和实例方法..............................................................................................................................189

10.5.3 虚拟方法.........................................................................................................................................190

10.5.4 覆盖方法.........................................................................................................................................191 viii Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

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10.5.5 抽象方法.........................................................................................................................................193

10.5.6 外部方法.........................................................................................................................................194

10.5.7 方法主体.........................................................................................................................................195

10.5.8 方法重载.........................................................................................................................................195

10.6 属性........................................................................................................................................................195

10.6.1 静态属性.........................................................................................................................................196

10.6.2 虚拟属性.........................................................................................................................................196

10.6.3 覆盖属性.........................................................................................................................................197

10.6.4 抽象属性.........................................................................................................................................198

10.6.5 访问符.............................................................................................................................................198

10.7 事件........................................................................................................................................................203

10.8 索引........................................................................................................................................................206

10.8.1 索引重载.........................................................................................................................................209

10.8.2 虚拟索引.........................................................................................................................................209

10.8.3 覆盖索引.........................................................................................................................................209

10.8.4 抽象索引.........................................................................................................................................210

10.9 操作符....................................................................................................................................................210

10.9.1 一元操作符.....................................................................................................................................211

10.9.2 二元操作符.....................................................................................................................................211

10.9.3 转换操作符.....................................................................................................................................212

10.10 实例构造函数......................................................................................................................................213

10.10.1 构造函数初始化函数.....................................................................................................................214

10.10.2 实例变量初始化函数.....................................................................................................................214

10.10.3 构造函数执行...............................................................................................................................214

10.10.4 默认构造函数...............................................................................................................................216

10.10.5 私有构造函数...............................................................................................................................217

10.10.6 可选的构造函数参数.....................................................................................................................217

10.11 析构函数..............................................................................................................................................217

10.12 静态构造函数......................................................................................................................................218

10.12.1 类加载和初始化............................................................................................................................219

11. 结构..............................................................................................................................................................221

11.1 结构声明................................................................................................................................................221

11.1.1 结构修饰符.....................................................................................................................................221

11.1.2 接口.................................................................................................................................................221

11.1.3 结构体.............................................................................................................................................221

11.2 结构成员................................................................................................................................................221

11.3 结构例子................................................................................................................................................221

11.3.1 数据库整数类型..............................................................................................................................221

11.3.2 数据库布尔类型..............................................................................................................................223

12. 数组..............................................................................................................................................................225

12.1 数组类型................................................................................................................................................225

12.1.1 System.Array 类型...................................................................................................................226

12.2 数组创建................................................................................................................................................226

12.3 数组元素访问........................................................................................................................................226 Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved. ix

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12.4 数组成员................................................................................................................................................226

12.5 数组协方差............................................................................................................................................226

12.6 数组初始化函数....................................................................................................................................227

13. 接口..............................................................................................................................................................229

13.1 接口声明................................................................................................................................................229

13.1.1 接口修饰符.....................................................................................................................................229

13.1.2 基本接口.........................................................................................................................................229

13.1.3 接口主体.........................................................................................................................................230

13.2 接口成员................................................................................................................................................230

13.2.1 接口方法.........................................................................................................................................231

13.2.2 接口属性.........................................................................................................................................231

13.2.3 接口事件.........................................................................................................................................232

13.2.4 接口索引.........................................................................................................................................232

13.2.5 接口成员访问.................................................................................................................................232

13.3 完全有效的接口成员名称.....................................................................................................................234

13.4 接口实现................................................................................................................................................234

13.4.1 显式接口成员实现程序...................................................................................................................235

13.4.2 接口映射.........................................................................................................................................237

13.4.3 接口实现程序继承...........................................................................................................................239

13.4.4 接口重新实现程序...........................................................................................................................240

13.4.5 抽象类和接口.................................................................................................................................242

14. 枚举..............................................................................................................................................................243

14.1 枚举声明................................................................................................................................................243

14.2 枚举成员................................................................................................................................................244

14.3 枚举数值和操作....................................................................................................................................246

15. 代表..............................................................................................................................................................247

15.1 代表声明................................................................................................................................................247

15.1.1 可合并的代表类型...........................................................................................................................248

15.2 代表实例化............................................................................................................................................248

15.3 多点传送代表........................................................................................................................................248

15.4 代表调用................................................................................................................................................248

16. 异常..............................................................................................................................................................249

16.1 异常的产生............................................................................................................................................249

16.2 System.Exception 类......................................................................................................................249

16.3 异常怎样被处理....................................................................................................................................249

16.4 通用异常类............................................................................................................................................250

17. 属性..............................................................................................................................................................251

17.1 属性类....................................................................................................................................................251

17.1.1 AttributeUsage 属性..............................................................................................................251

17.1.2 位置的和名称的参数.......................................................................................................................252

17.1.3 属性参数类型.................................................................................................................................252

17.2 规范........................................................................................................................................................253 x Confidential Material – Copyright  Microsoft Corporation 1999-2000. All Rights Reserved.

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17.3 属性实例................................................................................................................................................255

17.3.1 一个属性的编译..............................................................................................................................255

17.3.2 一个属性实例的运行时检索...........................................................................................................256

17.4 保留的属性............................................................................................................................................256

17.4.1 AttributeUsage 属性..............................................................................................................256

17.4.2 条件属性.........................................................................................................................................257

17.4.3 废弃的属性.....................................................................................................................................259

18. 危险代码......................................................................................................................................................261

18.1 危险代码................................................................................................................................................261

18.2 指针类型................................................................................................................................................261

19. 互用性..........................................................................................................................................................263

19.1 COMImport 属性................................................................................................................................263

19.2 COMRegisterFunction 属性............................................................................................................263

19.3 COMSourceInterfaces 属性............................................................................................................264

19.4 COMVisible 属性...............................................................................................................................264

19.5 DispId 属性.......................................................................................................................................264

19.6 DllImport 属性................................................................................................................................264

19.7 FieldOffset 属性.............................................................................................................................265

19.8 GlobalObject 属性...........................................................................................................................265

19.9 Guid 属性...........................................................................................................................................266

19.10 HasDefaultInterface 属性.........................................................................................................266

19.11 ImportedFromTypeLib 属性.........................................................................................................266

19.12 In 和 Out 属性.................................................................................................................................266

19.13 InterfaceType 属性.................................................