C Sharp (programming language)

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C♯
C Sharp wordmark.svg
Paradigm(s)multi-paradigm: structured, imperative, object-oriented, event-driven, functional, generic, reflective, concurrent
Appeared in2000
Designed byMicrosoft
DeveloperMicrosoft
Stable release5.0 (August 15, 2012; 17 months ago (2012-08-15))
Typing disciplinestatic, dynamic,[1] strong, safe, nominative, partially inferred
Major implementationsVisual C♯, .NET Framework, Mono, DotGNU
Dialects, Spec#, Polyphonic C♯
Influenced byC++,[2] Eiffel, Java,[2] Modula-3, Object Pascal,[3] ML, Icon, Haskell, , F#[note 1]
InfluencedD, F#, Java,[4] Monkey, Nemerle, Vala
PlatformCommon Language Infrastructure
LicenseCLR is proprietary, Mono compiler is dual GPLv3, MIT/X11 and libraries are LGPLv2, DotGNU is dual GPL and LGPLv2
Usual filename extensions.cs
 
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C♯
C Sharp wordmark.svg
Paradigm(s)multi-paradigm: structured, imperative, object-oriented, event-driven, functional, generic, reflective, concurrent
Appeared in2000
Designed byMicrosoft
DeveloperMicrosoft
Stable release5.0 (August 15, 2012; 17 months ago (2012-08-15))
Typing disciplinestatic, dynamic,[1] strong, safe, nominative, partially inferred
Major implementationsVisual C♯, .NET Framework, Mono, DotGNU
Dialects, Spec#, Polyphonic C♯
Influenced byC++,[2] Eiffel, Java,[2] Modula-3, Object Pascal,[3] ML, Icon, Haskell, , F#[note 1]
InfluencedD, F#, Java,[4] Monkey, Nemerle, Vala
PlatformCommon Language Infrastructure
LicenseCLR is proprietary, Mono compiler is dual GPLv3, MIT/X11 and libraries are LGPLv2, DotGNU is dual GPL and LGPLv2
Usual filename extensions.cs

C♯[note 2] (pronounced see sharp) is a multi-paradigm programming language encompassing strong typing, imperative, declarative, functional, procedural, generic, object-oriented (class-based), and component-oriented programming disciplines. It was developed by Microsoft within its .NET initiative and later approved as a standard by Ecma (ECMA-334) and ISO (ISO/IEC 23270:2006). C♯ is one of the programming languages designed for the Common Language Infrastructure.

C♯ is intended to be a simple, modern, general-purpose, object-oriented programming language.[5] Its development team is led by Anders Hejlsberg. The most recent version is C♯ 5.0, which was released on August 15, 2012.

Design goals[edit]

The ECMA standard lists these design goals for C#:[5]

Name[edit]

The name "C sharp" was inspired by musical notation where a sharp indicates that the written note should be made a semitone higher in pitch.[6] This is similar to the language name of C++, where "++" indicates that a variable should be incremented by 1. The sharp symbol also resembles a ligature of four "+" symbols (in a two-by-two grid), further implying that the language is an increment of C++.

Due to technical limitations of display (standard fonts, browsers, etc.) and the fact that the sharp symbol (U+266F music sharp sign (HTML: ♯)) is not present on the standard keyboard, the number sign (U+0023 # number sign (HTML: #)) was chosen to represent the sharp symbol in the written name of the programming language.[7] This convention is reflected in the ECMA-334 C# Language Specification.[5] However, when it is practical to do so (for example, in advertising or in box art[8]), Microsoft uses the intended musical symbol.

The "sharp" suffix has been used by a number of other .NET languages that are variants of existing languages, including J# (a .NET language also designed by Microsoft that is derived from Java 1.1), A# (from Ada), and the functional programming language F#.[9] The original implementation of Eiffel for .NET was called Eiffel#,[10] a name retired since the full Eiffel language is now supported. The suffix has also been used for libraries, such as Gtk# (a .NET wrapper for GTK+ and other GNOME libraries), Cocoa# (a wrapper for Cocoa).

History[edit]

During the development of the .NET Framework, the class libraries were originally written using a managed code compiler system called Simple Managed C (SMC).[11][12][13] In January 1999, Anders Hejlsberg formed a team to build a new language at the time called Cool, which stood for "C-like Object Oriented Language".[14] Microsoft had considered keeping the name "Cool" as the final name of the language, but chose not to do so for trademark reasons. By the time the .NET project was publicly announced at the July 2000 Professional Developers Conference, the language had been renamed C#, and the class libraries and ASP.NET runtime had been ported to C#.

C#'s principal designer and lead architect at Microsoft is Anders Hejlsberg, who was previously involved with the design of Turbo Pascal, Embarcadero Delphi (formerly CodeGear Delphi, Inprise Delphi and Borland Delphi), and Visual J++. In interviews and technical papers he has stated that flaws[citation needed] in most major programming languages (e.g. C++, Java, Delphi, and Smalltalk) drove the fundamentals of the Common Language Runtime (CLR), which, in turn, drove the design of the C# language itself.

James Gosling, who created the Java programming language in 1994, and Bill Joy, a co-founder of Sun Microsystems, the originator of Java, called C# an "imitation" of Java; Gosling further said that "[C# is] sort of Java with reliability, productivity and security deleted."[15][16] Klaus Kreft and Angelika Langer (authors of a C++ streams book) stated in a blog post that "Java and C# are almost identical programming languages. Boring repetition that lacks innovation,"[17] "Hardly anybody will claim that Java or C# are revolutionary programming languages that changed the way we write programs," and "C# borrowed a lot from Java - and vice versa. Now that C# supports boxing and unboxing, we'll have a very similar feature in Java."[18] In July 2000, Anders Hejlsberg said that C# is "not a Java clone" and is "much closer to C++" in its design.[19]

Since the release of C# 2.0 in November 2005, the C# and Java languages have evolved on increasingly divergent trajectories, becoming somewhat less similar. One of the first major departures came with the addition of generics to both languages, with vastly different implementations. C# makes use of reification to provide "first-class" generic objects that can be used like any other class, with code generation performed at class-load time.[20] By contrast, Java's generics are essentially a language syntax feature, and they do not affect the generated byte code, because the compiler performs type erasure on the generic type information after it has verified its correctness.[21]

Furthermore, C# has added several major features to accommodate functional-style programming, culminating in the LINQ extensions released with C# 3.0 and its supporting framework of lambda expressions, extension methods, and anonymous types.[22] These features enable C# programmers to use functional programming techniques, such as closures, when it is advantageous to their application. The LINQ extensions and the functional imports help developers reduce the amount of "boilerplate" code that is included in common tasks like querying a database, parsing an xml file, or searching through a data structure, shifting the emphasis onto the actual program logic to help improve readability and maintainability.[23]

C# used to have a mascot called Andy (named after Anders Hejlsberg). It was retired on Jan 29, 2004.[24]

C# was originally submitted for review to the ISO subcommittee JTC 1/SC 22[25] under ISO/IEC 23270:2003,[26] which is now withdrawn. It was then approved under ISO/IEC 23270:2006.[27]

Versions[edit]

In the course of its development, the C# language has gone through several versions:

VersionCLR[28]Language specificationDate.NET FrameworkVisual Studio
ECMAISO/IECMicrosoft
C# 1.01.0December 2002April 2003January 2002January 2002.NET Framework 1.0Visual Studio .NET 2002
C# 1.21.1October 2003April 2003.NET Framework 1.1Visual Studio .NET 2003
C# 2.02.0June 2006September 2006September 2005[A]November 2005.NET Framework 2.0Visual Studio 2005
C# 3.02.0
2.0 SP1
None[B]August 2007November 2007

.NET Framework 2.0 (Except LINQ/Query Extensions)[29]
.NET Framework 3.0 (Except LINQ/Query Extensions)[29]
.NET Framework 3.5

Visual Studio 2008
Visual Studio 2010
C# 4.04.0[C]April 2010April 2010.NET Framework 4Visual Studio 2010
C# 5.04.5[D]June 2013August 2012.NET Framework 4.5Visual Studio 2012
A The Microsoft C# 2.0 specification document only contains the new 2.0 features. For older features use the 1.2 specification above.
B No ECMA or ISO/IEC specifications exist for C# 3.0, 4.0 or 5.0.
C There was no CLR version 3.0.
D CLR documentation refers to as 4.5 but Environment.Version points to 4.0.[30]
Summary of versions
C# 2.0C# 3.0C# 4.0C# 5.0 [31]Future
Features
added
  • Generics
  • Partial types
  • Anonymous methods
  • Iterators
  • Nullable types
  • Private setters (properties)
  • Method group conversions (delegates)
  • Covariance and Contra-variance
  • Static classes
  • Implicitly typed local variables
  • Object and collection initializers
  • Auto-Implemented properties
  • Anonymous types
  • Extension methods
  • Query expressions
  • Lambda expressions
  • Expression trees
  • Partial Methods
  • Dynamic binding
  • Named and optional arguments
  • Generic co- and contravariance
  • Embedded interop types ("NoPIA")
  • Asynchronous methods
  • Caller info attributes
C# 5.0
  • Compiler-as-a-service (Roslyn)
C# 6.0
  • Import type members into namespace
  • Succinct syntax for primary constructors
  • Readonly properties
  • Property expressions (property lambdas)
  • Method expressions
  • Parameter arrays for IEnumerable interfaces
  • Succinct null checking
  • Multiple return values
  • Constructor type inference

Syntax[edit]

C# has the following syntax:

Distinguishing features[edit]

Note: The following description is based on the language standard and other documents listed in the "External links" section.

By design, C# is the programming language that most directly reflects the underlying Common Language Infrastructure (CLI).[32] Most of its intrinsic types correspond to value-types implemented by the CLI framework. However, the language specification does not state the code generation requirements of the compiler: that is, it does not state that a C# compiler must target a Common Language Runtime, or generate Common Intermediate Language (CIL), or generate any other specific format. Theoretically, a C# compiler could generate machine code like traditional compilers of C++ or Fortran. Some notable features of C# that distinguish it from C and C++ (and Java, where noted) are:

Common type system[edit]

C# has a unified type system. This unified type system is called Common Type System (CTS).[34]

A unified type system implies that all types, including primitives such as integers, are subclasses of the System.Object class. For example, every type inherits a ToString() method.

Categories of data types[edit]

CTS separates data types into two categories:[34]

  1. Reference types
  2. Value types

Instances of value types do not have referential identity nor referential comparison semantics - equality and inequality comparisons for value types compare the actual data values within the instances, unless the corresponding operators are overloaded. Value types are derived from System.ValueType, always have a default value, and can always be created and copied. Some other limitations on value types are that they cannot derive from each other (but can implement interfaces) and cannot have an explicit default (parameterless) constructor. Examples of value types are all primitive types, such as int (a signed 32-bit integer), float (a 32-bit IEEE floating-point number), char (a 16-bit Unicode code unit), and System.DateTime (identifies a specific point in time with nanosecond precision). Other examples are enum (enumerations) and struct (user defined structures).

In contrast, reference types have the notion of referential identity - each instance of a reference type is inherently distinct from every other instance, even if the data within both instances is the same. This is reflected in default equality and inequality comparisons for reference types, which test for referential rather than structural equality, unless the corresponding operators are overloaded (such as the case for System.String). In general, it is not always possible to create an instance of a reference type, nor to copy an existing instance, or perform a value comparison on two existing instances, though specific reference types can provide such services by exposing a public constructor or implementing a corresponding interface (such as ICloneable or IComparable). Examples of reference types are object (the ultimate base class for all other C# classes), System.String (a string of Unicode characters), and System.Array (a base class for all C# arrays).

Both type categories are extensible with user-defined types.

Boxing and unboxing[edit]

Boxing is the operation of converting a value-type object into a value of a corresponding reference type.[34] Boxing in C# is implicit.

Unboxing is the operation of converting a value of a reference type (previously boxed) into a value of a value type.[34] Unboxing in C# requires an explicit type cast. A boxed object of type T can only be unboxed to a T (or a nullable T).[35]

Example:

 int foo1 = 42;         // Value type. object bar = foo1;     // foo is boxed to bar. int foo2 = (int)bar;  // Unboxed back to value type. 

Generics[edit]

Generics were added to version 2.0 of the C# language. Generics use type parameters, which make it possible to design classes and methods that do not specify the type used until the class or method is instantiated. The main advantage is that one can use generic type parameters to create classes and methods that can be used without incurring the cost of runtime casts or boxing operations, as shown here:[36]

 // Declare the generic class.   public class GenericList<T> {     void Add(T input) { } }   class TestGenericList {     private class ExampleClass { }     static void Main()     {         // Declare a list of type int.         GenericList<int> list1 = new GenericList<int>();           // Declare a list of type string.         GenericList<string> list2 = new GenericList<string>();           // Declare a list of type ExampleClass.         GenericList<ExampleClass> list3 = new GenericList<ExampleClass>();     } } 

When compared with C++ templates, C# generics can provide enhanced safety, but also have somewhat limited capabilities.[37] For example, it is not possible to call arithmetic operators on a C# generic type.[38]

Preprocessor[edit]

C# features "preprocessor directives"[39] (though it does not have an actual preprocessor) based on the C preprocessor that allow programmers to define symbols, but not macros. Conditionals such as #if, #endif, and #else are also provided. Directives such as #region give hints to editors for code folding.

 public class Foo {     #region Constructors     public Foo() {}     public Foo(int firstParam) {}     #endregion       #region Procedures     public void IntBar(int firstParam) {}     public void StrBar(string firstParam) {}     public void BoolBar(bool firstParam) {}     #endregion } 

Code comments[edit]

C# utilizes a double slash (//) to indicate the rest of the line is a comment. This is inherited from C++.

 public class Foo {     // a comment     public static void Bar(int firstParam) {}  // also a comment } 

Multi-line comments can start with slash-asterisk (/*) and end asterisk-slash (*/). This is inherited from standard C.

 public class Foo {     /* A Multi-Line        comment  */     public static void Bar(int firstParam) {} } 

XML documentation system[edit]

C#'s documentation system is similar to Java's Javadoc, but based on XML. Two methods of documentation are currently supported by the C# compiler.

Single-line documentation comments, such as those commonly found in Visual Studio generated code, are indicated on a line beginning with ///.

 public class Foo {     /// <summary>A summary of the method.</summary>     /// <param name="firstParam">A description of the parameter.</param>     /// <remarks>Remarks about the method.</remarks>     public static void Bar(int firstParam) {} } 

Multi-line documentation comments, while defined in the version 1.0 language specification, were not supported until the .NET 1.1 release.[40] These comments start with slash-asterisk-asterisk (/**) and end asterisk-slash (*/).[41]

 public class Foo {     /** <summary>A summary of the method.</summary>      *  <param name="firstParam">A description of the parameter.</param>      *  <remarks>Remarks about the method.</remarks> */     public static void Bar(int firstParam) {} } 

Note there are some stringent criteria regarding white space and XML documentation when using the slash/asterisk/asterisk (/**) technique.

This code block:

 /**  * <summary>  * A summary of the method.</summary>*/ 

produces a different XML comment from this code block:[41]

 /**  * <summary>    A summary of the method.</summary>*/ 

Syntax for documentation comments and their XML markup is defined in a non-normative annex of the ECMA C# standard. The same standard also defines rules for processing of such comments, and their transformation to a plain XML document with precise rules for mapping of CLI identifiers to their related documentation elements. This allows any C# IDE or other development tool to find documentation for any symbol in the code in a certain well-defined way.

Libraries[edit]

The C# specification details a minimum set of types and class libraries that the compiler expects to have available. In practice, C# is most often used with some implementation of the Common Language Infrastructure (CLI), which is standardized as ECMA-335 Common Language Infrastructure (CLI).

"Hello world" example[edit]

The following is a very simple C# program, a version of the classic "Hello world" example:

 using System;   class Program {     static void Main()     {         Console.WriteLine("Hello world!");     } } 

The effect is to write the following text to the output console:

 Hello world! 

Each line has a purpose:

 using System; 

The above line of code tells the compiler to use System as a candidate prefix for types used in the source code. In this case, when the compiler sees use of the Console type later in the source code, it tries to find a type named Console, first in the current assembly, followed by all referenced assemblies. In this case the compiler fails to find such a type, since the name of the type is actually System.Console. The compiler then attempts to find a type named System.Console by using the System prefix from the using statement, and this time it succeeds. The using statement allows the programmer to state all candidate prefixes to use during compilation instead of always using full type names.

 class Program 

Above is a class definition. Everything between the following pair of braces describes Program.

 static void Main() 

This declares the class member method where the program begins execution. The .NET runtime calls the Main method. (Note: Main may also be called from elsewhere, like any other method, e.g. from another method of Program.) The static keyword makes the method accessible without an instance of Program. Each console application's Main entry point must be declared static. Otherwise, the program would require an instance, but any instance would require a program. To avoid that irresolvable circular dependency, C# compilers processing console applications (like that above) report an error, if there is no static Main method. The void keyword declares that Main has no return value.

 Console.WriteLine("Hello world!"); 

This line writes the output. Console is a static class in the System namespace. It provides an interface to the standard input, output, and error streams for console applications. The program calls the Console method WriteLine, which displays on the console a line with the argument, the string "Hello world!".

A GUI example:

 using System.Windows.Forms;   class Program {     static void Main()     {         MessageBox.Show("Hello world!");     } } 

This example is similar to the previous example, except that it generates a dialog box that contains the message "Hello world!" instead of writing it to the console.

Standardization and licensing[edit]

In August 2000, Microsoft Corporation, Hewlett-Packard and Intel Corporation co-sponsored the submission of specifications for C# as well as the Common Language Infrastructure (CLI) to the standards organization Ecma International. In December 2001, ECMA released ECMA-334 C# Language Specification. C# became an ISO standard in 2003 (ISO/IEC 23270:2003 - Information technology — Programming languages — C#). ECMA had previously adopted equivalent specifications as the 2nd edition of C#, in December 2002.

In June 2005, ECMA approved edition 3 of the C# specification, and updated ECMA-334. Additions included partial classes, anonymous methods, nullable types, and generics (similar to C++ templates).

In July 2005, ECMA submitted the standards and related TRs to ISO/IEC JTC 1 via the latter's Fast-Track process. This process usually takes 6–9 months.

The C# language definition and the CLI are standardized under ISO and Ecma standards that provide reasonable and non-discriminatory licensing protection from patent claims. However, Microsoft uses C# and the CLI in its Base Class Library (BCL) that is the foundation of its proprietary .NET framework, and which provides a variety of non-standardized classes (extended I/O, GUI, Web services, etc.). Some cases where Microsoft patents apply to standards used in the .NET framework are documented by Microsoft and the applicable patents are available on either RAND terms or through Microsoft's Open Specification Promise that releases patent rights to the public,[42] but there is some concern and debate as to whether there are additional aspects patented by Microsoft that are not covered, which may deter independent implementations of the full framework.

Microsoft has agreed not to sue open source developers for violating patents in non-profit projects for the part of the framework that is covered by the OSP.[43] Microsoft has also agreed not to enforce patents relating to Novell products against Novell's paying customers[44] with the exception of a list of products that do not explicitly mention C#, .NET or Novell's implementation of .NET (The Mono Project).[45] However, Novell maintains that Mono does not infringe any Microsoft patents.[46] Microsoft has also made a specific agreement not to enforce patent rights related to the Moonlight browser plugin, which depends on Mono, provided it is obtained through Novell.[47]

In a note posted on the Free Software Foundation's news website in June 2009, Richard Stallman warned that he believes that "Microsoft is probably planning to force all free C# implementations underground some day using software patents", and recommended that developers avoid taking what he described as the "gratuitous risk" associated with "depend[ing] on the free C# implementations".[48] The Free Software Foundation later reiterated its warnings,[49] claiming that the extension of Microsoft Community Promise to the C# and the CLI ECMA specifications[50] would not prevent Microsoft from harming free implementations of C#, because many specific Windows libraries included with .NET or Mono were not covered by this promise.

Implementations[edit]

The reference C# compiler is Microsoft Visual C#, which is closed-source.

Other C# compilers exist, often including an implementation of the Common Language Infrastructure and the .NET class libraries up to .NET 2.0:

See also[edit]

Notes[edit]

  1. ^ for async
  2. ^ By convention, a number sign is used for the second character in normal text; in artistic representations, sometimes a true sharp sign is used: C♯.

References[edit]

  1. ^ Torgersen, Mads (October 27, 2008). "New features in C# 4.0". Microsoft. Retrieved October 28, 2008. 
  2. ^ a b Naugler, David (May 2007). "C# 2.0 for C++ and Java programmer: conference workshop". Journal of Computing Sciences in Colleges 22 (5). "Although C# has been strongly influenced by Java it has also been strongly influenced by C++ and is best viewed as a descendant of both C++ and Java." 
  3. ^ Hamilton, Naomi (October 1, 2008). "The A-Z of Programming Languages: C#". Computerworld. Retrieved February 12, 2010. "We all stand on the shoulders of giants here and every language builds on what went before it so we owe a lot to C, C++, Java, Delphi, all of these other things that came before us. (Anders Hejlsberg)" 
  4. ^ Cornelius, Barry (December 1, 2005). "Java 5 catches up with C#". University of Oxford Computing Services. Retrieved June 18, 2009. "In my opinion, it is C# that has caused these radical changes to the Java language. (Barry Cornelius)" 
  5. ^ a b c C# Language Specification (4th ed.). Ecma International. June 2006. Retrieved January 26, 2012. 
  6. ^ Kovacs, James (September 7, 2007). "C#/.NET History Lesson". Retrieved June 18, 2009. 
  7. ^ "Microsoft C# FAQ". Microsoft. Retrieved March 25, 2008. [dead link]
  8. ^ "Visual C#.net Standard" (JPEG). Microsoft. September 4, 2003. Retrieved June 18, 2009. 
  9. ^ "F# FAQ". Microsoft Research. Retrieved June 18, 2009. [dead link]
  10. ^ Simon, Raphael; Stapf, Emmanuel; Meyer, Bertrand (June 2002). "Full Eiffel on the .NET Framework". Microsoft. Retrieved June 18, 2009. 
  11. ^ Zander, Jason (November 24, 2008). "Couple of Historical Facts". Retrieved February 23, 2009. 
  12. ^ "C# 3.0 New Features". Retrieved June 9, 20010. 
  13. ^ Guthrie, Scott (November 28, 2006). "What language was ASP.Net originally written in?". Retrieved February 21, 2008. 
  14. ^ Hamilton, Naomi (October 1, 2008). "The A-Z of Programming Languages: C#". Computerworld. Retrieved October 1, 2008. 
  15. ^ Wylie Wong (2002). "Why Microsoft's C# isn't". CNET: CBS Interactive. Retrieved November 14, 2009. 
  16. ^ Bill Joy (February 7, 2002). "Microsoft's blind spot". cnet.com. Retrieved January 12, 2010. 
  17. ^ Klaus Kreft and Angelika Langer (2003). "After Java and C# - what is next?". Retrieved June 18, 2013. 
  18. ^ Klaus Kreft and Angelika Langer (July 3, 2003). "After Java and C# - what is next?". artima.com. Retrieved January 12, 2010. 
  19. ^ Osborn, John (August 1, 2000). Deep Inside C#: An Interview with Microsoft Chief Architect Anders Hejlsberg. O'Reilly Media. Retrieved November 14, 2009 
  20. ^ "Generics (C# Programming Guide)". Microsoft. Retrieved March 21, 2011. 
  21. ^ Bracha, Gilad (July 5, 2004). "Generics in the Java Programming Language". Sun Microsystems. Retrieved March 21, 2011. 
  22. ^ Don Box and Anders Hejlsberg (February 2007). "LINQ: .NET Language-Integrated Query". Microsoft. Retrieved March 21, 2011. 
  23. ^ Mercer, Ian (April 15, 2010). "Why functional programming and LINQ is often better than procedural code". abodit.com. Retrieved March 21, 2011. 
  24. ^ "Andy Retires". Dan Fernandez's Blog. Blogs.msdn.com. January 29, 2004. Retrieved October 4, 2012. 
  25. ^ "Technical committees - JTC 1/SC 22 - Programming languages, their environments and system software interfaces". ISO. Retrieved October 4, 2012. 
  26. ^ "ISO/IEC 23270:2003 - Information technology - C# Language Specification". Iso.org. August 23, 2006. Retrieved October 4, 2012. 
  27. ^ "ISO/IEC 23270:2006 - Information technology - Programming languages - C#". Iso.org. January 26, 2012. Retrieved October 4, 2012. 
  28. ^ "Common Language Runtime (CLR)". Microsoft Developer Network. .NET Framework 4.5. Microsoft. Retrieved 2013-11-26. 
  29. ^ a b "Using C# 3.0 from .NET 2.0". Danielmoth.com. May 13, 2007. Retrieved October 4, 2012. 
  30. ^ Skeet, Jon (September 2013). C# in Depth (3rd ed.). Manning Publications Co. p. 559. ISBN 9781617291340 
  31. ^ Hejlsberg, Anders. "Future directions for C# and Visual Basic". C# lead architect. Channel 9. Retrieved September 21, 2011. 
  32. ^ Visual Studio 2010 and .NET 4 Six-in-One. Wrox Press. 2010. ISBN 0470499486. 
  33. ^ Venners, Bill; Eckel, Bruce (August 18, 2003). "The Trouble with Checked Exceptions". Retrieved March 30, 2010. 
  34. ^ a b c d Archer, Tom (2001). "Part 2, Chapter 4: The Type System". Inside C#. Redmond, Washington: Microsoft Press. ISBN 0-7356-1288-9. 
  35. ^ Lippert, Eric (March 19, 2009). "Representation and Identity". Fabulous Adventures In Coding. Blogs.msdn.com. Retrieved October 4, 2012. 
  36. ^ "Generics (C# Programming Guide)". Microsoft. Retrieved August 7, 2011. 
  37. ^ "An Introduction to C# Generics". Microsoft. 
  38. ^ "Differences Between C++ Templates and C# Generics". Microsoft. 
  39. ^ "C# Preprocessor Directives". C# Language Reference. Microsoft. Retrieved June 18, 2009. 
  40. ^ Horton, Anson (September 11, 2006). "C# XML documentation comments FAQ". Retrieved December 11, 2007. 
  41. ^ a b "Delimiters for Documentation Tags". C# Programmer's Reference. Microsoft. January 1, 1970 GMT. Retrieved June 18, 2009. 
  42. ^ "Interoperability Principles". 
  43. ^ "Patent Pledge for Open Source Developers". 
  44. ^ "Patent Cooperation Agreement - Microsoft & Novell Interoperability Collaboration". Microsoft. November 2, 2006. Retrieved July 5, 2009. "Microsoft, on behalf of itself and its Subsidiaries (collectively "Microsoft"), hereby covenants not to sue Novell's Customers and Novell's Subsidiaries' Customers for infringement under Covered Patents of Microsoft on account of such a Customer's use of specific copies of a Covered Product as distributed by Novell or its Subsidiaries (collectively "Novell") for which Novell has received Revenue (directly or indirectly) for such specific copies; provided the foregoing covenant is limited to use by such Customer (i) of such specific copies that are authorized by Novell in consideration for such Revenue, and (ii) within the scope authorized by Novell in consideration for such Revenue." 
  45. ^ "Definitions". Microsoft. November 2, 2006. Retrieved July 5, 2009. 
  46. ^ Steinman, Justin (November 7, 2006). "Novell Answers Questions from the Community". Retrieved July 5, 2009. "We maintain that Mono does not infringe any Microsoft patents." 
  47. ^ "Covenant to Downstream Recipients of Moonlight - Microsoft & Novell Interoperability Collaboration". Microsoft. September 28, 2007. Retrieved March 8, 2008. ""Downstream Recipient" means an entity or individual that uses for its intended purpose a Moonlight Implementation obtained directly from Novell or through an Intermediate Recipient... Microsoft reserves the right to update (including discontinue) the foregoing covenant... "Moonlight Implementation" means only those specific portions of Moonlight 1.0 or Moonlight 1.1 that run only as a plug-in to a browser on a Personal Computer and are not licensed under GPLv3 or a Similar License." 
  48. ^ Stallman, Richard (June 26, 2009). "Why free software shouldn't depend on Mono or C#". Free Software Foundation. Retrieved July 2, 2009. "The danger is that Microsoft is probably planning to force all free C# implementations underground some day using software patents. ... We should systematically arrange to depend on the free C# implementations as little as possible. In other words, we should discourage people from writing programs in C#. Therefore, we should not include C# implementations in the default installation of GNU/Linux distributions, and we should distribute and recommend non-C# applications rather than comparable C# applications whenever possible." 
  49. ^ "Microsoft's Empty Promise". Free Software Foundation. July 16, 2009. Retrieved 2009-078-03. "Until that happens, free software developers still should not write software that depends on Mono. C# implementations can still be attacked by Microsoft's patents: the Community Promise is designed to give the company several outs, if it wants them. We don't want to see developers' hard work lost to the community, if we lose the ability to use Mono, and until we eliminate software patents altogether, using another language is the best way to prevent that from happening." 
  50. ^ "The ECMA C# and CLI Standards". July 6, 2009. Retrieved 2009-078-03. 
  51. ^ "Compatibility - Mono". Mono-project.com. December 19, 2011. Retrieved October 4, 2012. 

Further reading[edit]

External links[edit]