C Sharp (programming language)

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C Sharp (programming language)_table_infobox_0

C#C Sharp (programming language)_table_caption_0
ParadigmC Sharp (programming language)_header_cell_0_0_0 Structured, imperative, object-oriented, event-driven, task-driven, functional, generic, reflective, concurrentC Sharp (programming language)_cell_0_0_1
FamilyC Sharp (programming language)_header_cell_0_1_0 CC Sharp (programming language)_cell_0_1_1
Designed byC Sharp (programming language)_header_cell_0_2_0 MicrosoftC Sharp (programming language)_cell_0_2_1
DeveloperC Sharp (programming language)_header_cell_0_3_0 MicrosoftC Sharp (programming language)_cell_0_3_1
First appearedC Sharp (programming language)_header_cell_0_4_0 2000; 20 years ago (2000)C Sharp (programming language)_cell_0_4_1
Stable releaseC Sharp (programming language)_header_cell_0_5_0 9.0
  / November 10, 2020; 34 days ago (2020-11-10)C Sharp (programming language)_cell_0_5_1
Typing disciplineC Sharp (programming language)_header_cell_0_6_0 Static, dynamic, strong, safe, nominative, partially inferredC Sharp (programming language)_cell_0_6_1
PlatformC Sharp (programming language)_header_cell_0_7_0 Common Language InfrastructureC Sharp (programming language)_cell_0_7_1
LicenseC Sharp (programming language)_header_cell_0_8_0 C Sharp (programming language)_cell_0_8_1
C Sharp (programming language)_header_cell_0_9_0 .cs, .csxC Sharp (programming language)_cell_0_9_1
WebsiteC Sharp (programming language)_header_cell_0_10_0 C Sharp (programming language)_cell_0_10_1
Major implementationsC Sharp (programming language)_header_cell_0_11_0
DialectsC Sharp (programming language)_header_cell_0_12_0
Influenced byC Sharp (programming language)_header_cell_0_13_0
InfluencedC Sharp (programming language)_header_cell_0_14_0

C# (pronounced see sharp, like the musical note C♯, but written with the number sign) is a general-purpose, multi-paradigm programming language encompassing static typing, strong typing, lexically scoped, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines. C Sharp (programming language)_sentence_0

C# was developed around 2000 by Microsoft as part of its .NET initiative and later approved as an international standard by Ecma (ECMA-334) in 2002 and ISO (ISO/IEC 23270) in 2003. C Sharp (programming language)_sentence_1

It was designed by Anders Hejlsberg, and its development team is currently led by Mads Torgersen, being one of the programming languages designed for the Common Language Infrastructure (CLI). C Sharp (programming language)_sentence_2

The most recent version is 9.0, which was released in 2020 in .NET 5.0 and included in Visual Studio 2019 version 16.8. C Sharp (programming language)_sentence_3

Mono is a free and open-source project to develop a cross-platform compiler and runtime environment (i.e. virtual machine) for the language. C Sharp (programming language)_sentence_4

Design goals C Sharp (programming language)_section_0

The Ecma standard lists these design goals for C#: C Sharp (programming language)_sentence_5

C Sharp (programming language)_unordered_list_0

  • The language is intended to be a simple, modern, general-purpose, object-oriented programming language.C Sharp (programming language)_item_0_0
  • The language, and implementations thereof, should provide support for software engineering principles such as strong type checking, array bounds checking, detection of attempts to use uninitialized variables, and automatic garbage collection. Software robustness, durability, and programmer productivity are important.C Sharp (programming language)_item_0_1
  • The language is intended for use in developing software components suitable for deployment in distributed environments.C Sharp (programming language)_item_0_2
  • Portability is very important for source code and programmers, especially those already familiar with C and C++.C Sharp (programming language)_item_0_3
  • Support for internationalization is very important.C Sharp (programming language)_item_0_4
  • C# is intended to be suitable for writing applications for both hosted and embedded systems, ranging from the very large that use sophisticated operating systems, down to the very small having dedicated functions.C Sharp (programming language)_item_0_5
  • Although C# applications are intended to be economical with regard to memory and processing power requirements, the language was not intended to compete directly on performance and size with C or assembly language.C Sharp (programming language)_item_0_6

History C Sharp (programming language)_section_1

During the development of the .NET Framework, the class libraries were originally written using a managed code compiler system called "Simple Managed C" (SMC). C Sharp (programming language)_sentence_6

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". C Sharp (programming language)_sentence_7

Microsoft had considered keeping the name "Cool" as the final name of the language, but chose not to do so for trademark reasons. C Sharp (programming language)_sentence_8

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 Sharp (programming language)_sentence_9

Hejlsberg is C#'s principal designer and lead architect at Microsoft, and was previously involved with the design of Turbo Pascal, Embarcadero Delphi (formerly CodeGear Delphi, Inprise Delphi and Borland Delphi), and Visual J++. C Sharp (programming language)_sentence_10

In interviews and technical papers he has stated that flaws 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. C Sharp (programming language)_sentence_11

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." C Sharp (programming language)_sentence_12

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. C Sharp (programming language)_sentence_13

Boring repetition that lacks innovation," "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. C Sharp (programming language)_sentence_14

Now that C# supports boxing and unboxing, we'll have a very similar feature in Java." C Sharp (programming language)_sentence_15

In July 2000, Hejlsberg said that C# is "not a Java clone" and is "much closer to C++" in its design. C Sharp (programming language)_sentence_16

Since the release of C# 2.0 in November 2005, the C# and Java languages have evolved on increasingly divergent trajectories, becoming two quite different languages. C Sharp (programming language)_sentence_17

One of the first major departures came with the addition of generics to both languages, with vastly different implementations. C Sharp (programming language)_sentence_18

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. C Sharp (programming language)_sentence_19

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. C Sharp (programming language)_sentence_20

These features enable C# programmers to use functional programming techniques, such as closures, when it is advantageous to their application. C Sharp (programming language)_sentence_21

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. C Sharp (programming language)_sentence_22

C# used to have a mascot called Andy (named after Anders Hejlsberg). C Sharp (programming language)_sentence_23

It was retired on January 29, 2004. C Sharp (programming language)_sentence_24

C# was originally submitted to the ISO subcommittee JTC 1/SC 22 for review, under ISO/IEC 23270:2003, was withdrawn and was then approved under ISO/IEC 23270:2006. C Sharp (programming language)_sentence_25

The 23270:2006 is withdrawned under 23270:2018 and approved with this version. C Sharp (programming language)_sentence_26

Name C Sharp (programming language)_section_2

Microsoft first used the name C# in 1988 for a variant of the C language designed for incremental compilation. C Sharp (programming language)_sentence_27

That project was not completed but the name lives on. C Sharp (programming language)_sentence_28

The name "C sharp" was inspired by the musical notation whereby a sharp symbol indicates that the written note should be made a semitone higher in pitch. C Sharp (programming language)_sentence_29

This is similar to the language name of C++, where "++" indicates that a variable should be incremented by 1 after being evaluated. C Sharp (programming language)_sentence_30

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++. C Sharp (programming language)_sentence_31

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 most keyboard layouts, the number sign (U+0023 # NUMBER SIGN (HTML # · #)) was chosen to approximate the sharp symbol in the written name of the programming language. C Sharp (programming language)_sentence_32

This convention is reflected in the ECMA-334 C# Language Specification. C Sharp (programming language)_sentence_33

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#. C Sharp (programming language)_sentence_34

The original implementation of Eiffel for .NET was called Eiffel#, a name retired since the full Eiffel language is now supported. C Sharp (programming language)_sentence_35

The suffix has also been used for libraries, such as Gtk# (a .NET wrapper for GTK+ and other GNOME libraries) and Cocoa# (a wrapper for Cocoa). C Sharp (programming language)_sentence_36

Versions C Sharp (programming language)_section_3

New features C Sharp (programming language)_section_4

C# 2.0 (2005) C Sharp (programming language)_section_5
C# 3.0 (2007) C Sharp (programming language)_section_6
C# 4.0 (2010) C Sharp (programming language)_section_7
C# 5.0[50] (2012) C Sharp (programming language)_section_8
C# 6.0 (2015) C Sharp (programming language)_section_9
C# 7.0[53][54] (2017) C Sharp (programming language)_section_10
C# 7.1[55] (2017) C Sharp (programming language)_section_11
C# 7.2[56] (2017) C Sharp (programming language)_section_12
C# 7.3[57] (2018) C Sharp (programming language)_section_13
C# 8.0[58] (2019) C Sharp (programming language)_section_14
C# 9.0[59] (2020) C Sharp (programming language)_section_15

Syntax C Sharp (programming language)_section_16

Main article: C Sharp syntax C Sharp (programming language)_sentence_37

See also: Syntax (programming languages) C Sharp (programming language)_sentence_38

The core syntax of the C# language is similar to that of other C-style languages such as C, C++ and Java, particularly: C Sharp (programming language)_sentence_39

C Sharp (programming language)_unordered_list_1

  • Semicolons are used to denote the end of a statement.C Sharp (programming language)_item_1_7
  • Curly brackets are used to group statements. Statements are commonly grouped into methods (functions), methods into classes, and classes into namespaces.C Sharp (programming language)_item_1_8
  • Variables are assigned using an equals sign, but compared using two consecutive equals signs.C Sharp (programming language)_item_1_9
  • Square brackets are used with arrays, both to declare them and to get a value at a given index in one of them.C Sharp (programming language)_item_1_10

Distinguishing features C Sharp (programming language)_section_17

See also: Comparison of C Sharp and Java C Sharp (programming language)_sentence_40

Some notable features of C# that distinguish it from C, C++, and Java where noted, are: C Sharp (programming language)_sentence_41

Portability C Sharp (programming language)_section_18

By design, C# is the programming language that most directly reflects the underlying Common Language Infrastructure (CLI). C Sharp (programming language)_sentence_42

Most of its intrinsic types correspond to value-types implemented by the CLI framework. C Sharp (programming language)_sentence_43

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. C Sharp (programming language)_sentence_44

Theoretically, a C# compiler could generate machine code like traditional compilers of C++ or Fortran. C Sharp (programming language)_sentence_45

Typing C Sharp (programming language)_section_19

C# supports strongly typed implicit variable declarations with the keyword var, and implicitly typed arrays with the keyword new[] followed by a collection initializer. C Sharp (programming language)_sentence_46

C# supports a strict Boolean data type, bool. C Sharp (programming language)_sentence_47

Statements that take conditions, such as while and if, require an expression of a type that implements the true operator, such as the Boolean type. C Sharp (programming language)_sentence_48

While C++ also has a Boolean type, it can be freely converted to and from integers, and expressions such as if (a) require only that a is convertible to bool, allowing a to be an int, or a pointer. C Sharp (programming language)_sentence_49

C# disallows this "integer meaning true or false" approach, on the grounds that forcing programmers to use expressions that return exactly bool can prevent certain types of programming mistakes such as if (a = b) (use of assignment = instead of equality ==). C Sharp (programming language)_sentence_50

C# is more type safe than C++. C Sharp (programming language)_sentence_51

The only implicit conversions by default are those that are considered safe, such as widening of integers. C Sharp (programming language)_sentence_52

This is enforced at compile-time, during JIT, and, in some cases, at runtime. C Sharp (programming language)_sentence_53

No implicit conversions occur between Booleans and integers, nor between enumeration members and integers (except for literal 0, which can be implicitly converted to any enumerated type). C Sharp (programming language)_sentence_54

Any user-defined conversion must be explicitly marked as explicit or implicit, unlike C++ copy constructors and conversion operators, which are both implicit by default. C Sharp (programming language)_sentence_55

C# has explicit support for covariance and contravariance in generic types, unlike C++ which has some degree of support for contravariance simply through the semantics of return types on virtual methods. C Sharp (programming language)_sentence_56

Enumeration members are placed in their own scope. C Sharp (programming language)_sentence_57

The C# language does not allow for global variables or functions. C Sharp (programming language)_sentence_58

All methods and members must be declared within classes. C Sharp (programming language)_sentence_59

Static members of public classes can substitute for global variables and functions. C Sharp (programming language)_sentence_60

Local variables cannot shadow variables of the enclosing block, unlike C and C++. C Sharp (programming language)_sentence_61

Metaprogramming C Sharp (programming language)_section_20

Metaprogramming via C# attributes is part of the language. C Sharp (programming language)_sentence_62

Many of these attributes duplicate the functionality of GCC's and VisualC++'s platform-dependent preprocessor directives. C Sharp (programming language)_sentence_63

Methods and functions C Sharp (programming language)_section_21

A method in C# is a member of a class that can be invoked as a function (a sequence of instructions), rather than the mere value-holding capability of a class property. C Sharp (programming language)_sentence_64

As in other syntactically similar languages, such as C++ and ANSI C, the signature of a method is a declaration comprising in order: any optional accessibility keywords (such as private), the explicit specification of its return type (such as int, or the keyword void if no value is returned), the name of the method, and finally, a parenthesized sequence of comma-separated parameter specifications, each consisting of a parameter's type, its formal name and optionally, a default value to be used whenever none is provided. C Sharp (programming language)_sentence_65

Certain specific kinds of methods, such as those that simply get or set a class property by return value or assignment, do not require a full signature, but in the general case, the definition of a class includes the full signature declaration of its methods. C Sharp (programming language)_sentence_66

Like C++, and unlike Java, C# programmers must use the scope modifier keyword virtual to allow methods to be overridden by subclasses. C Sharp (programming language)_sentence_67

Extension methods in C# allow programmers to use static methods as if they were methods from a class's method table, allowing programmers to add methods to an object that they feel should exist on that object and its derivatives. C Sharp (programming language)_sentence_68

The type dynamic allows for run-time method binding, allowing for JavaScript-like method calls and run-time object composition. C Sharp (programming language)_sentence_69

C# has support for strongly-typed function pointers via the keyword delegate. C Sharp (programming language)_sentence_70

Like the Qt framework's pseudo-C++ signal and slot, C# has semantics specifically surrounding publish-subscribe style events, though C# uses delegates to do so. C Sharp (programming language)_sentence_71

C# offers Java-like synchronized method calls, via the attribute [MethodImpl(MethodImplOptions.Synchronized)], and has support for mutually-exclusive locks via the keyword lock. C Sharp (programming language)_sentence_72

Property C Sharp (programming language)_section_22

C# supports class with properties. C Sharp (programming language)_sentence_73

The properties can be simple accessor functions with a backing field, or implement getter and setter functions. C Sharp (programming language)_sentence_74

Since C# 3.0 the syntactic sugar of auto-implemented properties is available, where the accessor (getter) and mutator (setter) encapsulate operations on a single attribute of a class. C Sharp (programming language)_sentence_75

Namespace C Sharp (programming language)_section_23

A C# namespace provides the same level of code isolation as a Java package or a C++ namespace, with very similar rules and features to a package. C Sharp (programming language)_sentence_76

Namespaces can be imported with the "using" syntax. C Sharp (programming language)_sentence_77

Memory access C Sharp (programming language)_section_24

In C#, memory address pointers can only be used within blocks specifically marked as unsafe, and programs with unsafe code need appropriate permissions to run. C Sharp (programming language)_sentence_78

Most object access is done through safe object references, which always either point to a "live" object or have the well-defined null value; it is impossible to obtain a reference to a "dead" object (one that has been garbage collected), or to a random block of memory. C Sharp (programming language)_sentence_79

An unsafe pointer can point to an instance of an 'unmanaged' value type that does not contain any references to garbage-collected objects, array, string, or a block of stack-allocated memory. C Sharp (programming language)_sentence_80

Code that is not marked as unsafe can still store and manipulate pointers through the System.IntPtr type, but it cannot dereference them. C Sharp (programming language)_sentence_81

Managed memory cannot be explicitly freed; instead, it is automatically garbage collected. C Sharp (programming language)_sentence_82

Garbage collection addresses the problem of memory leaks by freeing the programmer of responsibility for releasing memory that is no longer needed in most cases. C Sharp (programming language)_sentence_83

Code that retains references to objects longer than is required can still experience higher memory usage than necessary, however once the final reference to an object is released the memory is available for garbage collection. C Sharp (programming language)_sentence_84

Exception C Sharp (programming language)_section_25

A range of standard exceptions are available to programmers. C Sharp (programming language)_sentence_85

Methods in standard libraries regularly throw system exceptions in some circumstances and the range of exceptions thrown is normally documented. C Sharp (programming language)_sentence_86

Custom exception classes can be defined for classes allowing specific handling to be put in place for particular circumstances as needed. C Sharp (programming language)_sentence_87

Checked exceptions are not present in C# (in contrast to Java). C Sharp (programming language)_sentence_88

This has been a conscious decision based on the issues of scalability and versionability. C Sharp (programming language)_sentence_89

Polymorphism C Sharp (programming language)_section_26

Unlike C++, C# does not support multiple inheritance, although a class can implement any number of interfaces. C Sharp (programming language)_sentence_90

This was a design decision by the language's lead architect to avoid complications and to simplify architectural requirements throughout CLI. C Sharp (programming language)_sentence_91

When implementing multiple interfaces that contain a method with the same name and taking parameters of the same type in the same order (i.e. the same signature), similar to Java, C# allows both a single method to cover all interfaces and if necessary specific methods for each interface. C Sharp (programming language)_sentence_92

However, unlike Java, C# supports operator overloading. C Sharp (programming language)_sentence_93

Only the most commonly overloaded operators in C++ may be overloaded in C#. C Sharp (programming language)_sentence_94

Language Integrated Query (LINQ) C Sharp (programming language)_section_27

C# has the ability to utilize LINQ through the .NET Framework. C Sharp (programming language)_sentence_95

A developer can query a variety of data sources, provided IEnumerable<T> interface is implemented on the object. C Sharp (programming language)_sentence_96

This includes XML documents, an ADO.NET dataset, and SQL databases. C Sharp (programming language)_sentence_97

Using LINQ in C# brings advantages like Intellisense support, strong filtering capabilities, type safety with compile error checking ability, and consistency for querying data over a variety of sources. C Sharp (programming language)_sentence_98

There are several different language structures that can be utilized with C# and LINQ and they are query expressions, lambda expressions, anonymous types, implicitly typed variables, extension methods, and object initializers. C Sharp (programming language)_sentence_99

Functional programming C Sharp (programming language)_section_28

Though primarily an imperative language, C# 2.0 offered limited support for functional programming through first-class functions and closures in the form of anonymous delegates. C Sharp (programming language)_sentence_100

C# 3.0 expanded support for functional programming with the introduction of a lightweight syntax for lambda expressions, extension methods (an affordance for modules), and a list comprehension syntax in the form of a "query comprehension" language. C Sharp (programming language)_sentence_101

C# 7.0 adds features typically found in functional languages like tuples and pattern matching. C Sharp (programming language)_sentence_102

Common type system C Sharp (programming language)_section_29

C# has a unified type system. C Sharp (programming language)_sentence_103

This unified type system is called Common Type System (CTS). C Sharp (programming language)_sentence_104

A unified type system implies that all types, including primitives such as integers, are subclasses of the System.Object class. C Sharp (programming language)_sentence_105

For example, every type inherits a ToString() method. C Sharp (programming language)_sentence_106

Categories of data types C Sharp (programming language)_section_30

CTS separates data types into two categories: C Sharp (programming language)_sentence_107

C Sharp (programming language)_ordered_list_2

  1. Reference typesC Sharp (programming language)_item_2_11
  2. Value typesC Sharp (programming language)_item_2_12

Instances of value types neither have referential identity nor referential comparison semantics. C Sharp (programming language)_sentence_108

Equality and inequality comparisons for value types compare the actual data values within the instances, unless the corresponding operators are overloaded. C Sharp (programming language)_sentence_109

Value types are derived from System.ValueType, always have a default value, and can always be created and copied. C Sharp (programming language)_sentence_110

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. C Sharp (programming language)_sentence_111

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). C Sharp (programming language)_sentence_112

Other examples are enum (enumerations) and struct (user defined structures). C Sharp (programming language)_sentence_113

In contrast, reference types have the notion of referential identity, meaning that each instance of a reference type is inherently distinct from every other instance, even if the data within both instances is the same. C Sharp (programming language)_sentence_114

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). C Sharp (programming language)_sentence_115

Some operations are not always possible, such as creating an instance of a reference type, copying an existing instance, or performing a value comparison on two existing instances. C Sharp (programming language)_sentence_116

Though specific reference types can provide such services by exposing a public constructor or implementing a corresponding interface (such as ICloneable or IComparable). C Sharp (programming language)_sentence_117

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). C Sharp (programming language)_sentence_118

Both type categories are extensible with user-defined types. C Sharp (programming language)_sentence_119

Boxing and unboxing C Sharp (programming language)_section_31

Boxing is the operation of converting a value-type object into a value of a corresponding reference type. C Sharp (programming language)_sentence_120

Boxing in C# is implicit. C Sharp (programming language)_sentence_121

Unboxing is the operation of converting a value of a reference type (previously boxed) into a value of a value type. C Sharp (programming language)_sentence_122

Unboxing in C# requires an explicit type cast. C Sharp (programming language)_sentence_123

A boxed object of type T can only be unboxed to a T (or a nullable T). C Sharp (programming language)_sentence_124

Example: C Sharp (programming language)_sentence_125

Libraries C Sharp (programming language)_section_32

The C# specification details a minimum set of types and class libraries that the compiler expects to have available. C Sharp (programming language)_sentence_126

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). C Sharp (programming language)_sentence_127

In addition to the standard CLI specifications, there are many commercial and community class libraries that build on top of the .NET framework libraries to provide additional functionality. C Sharp (programming language)_sentence_128

C# can make calls to any library included in the List of .NET libraries and frameworks. C Sharp (programming language)_sentence_129

Examples C Sharp (programming language)_section_33

Hello World C Sharp (programming language)_section_34

The following is a very simple C# program, a version of the classic "Hello world" example: C Sharp (programming language)_sentence_130

This code will display this text in the console window: C Sharp (programming language)_sentence_131

Each line has a purpose: C Sharp (programming language)_sentence_132

The above line imports all types in the System namespace. C Sharp (programming language)_sentence_133

For example, the Console class used later in the source code is defined in the System namespace, meaning it can be used without supplying the full name of the type (which includes the namespace). C Sharp (programming language)_sentence_134

This line is a comment; it describes and documents the code for the programmer(s). C Sharp (programming language)_sentence_135

Above is a class definition for the Program class. C Sharp (programming language)_sentence_136

Everything that follows between the pair of braces describes that class. C Sharp (programming language)_sentence_137

The curly brackets demarcate the boundaries of a code block. C Sharp (programming language)_sentence_138

In this first instance, they are marking the start and end of the Program class. C Sharp (programming language)_sentence_139

This declares the class member method where the program begins execution. C Sharp (programming language)_sentence_140

The .NET runtime calls the Main method. C Sharp (programming language)_sentence_141

(Note: Main may also be called from elsewhere, like any other method, e.g. from another method of Program.) C Sharp (programming language)_sentence_142

The public keyword tells the compiler that the method can be called from anywhere by any class. C Sharp (programming language)_sentence_143

The static keyword makes the method accessible without an instance of Program. C Sharp (programming language)_sentence_144

Each console application's Main entry point must be declared static otherwise the program would require an instance of Program, but any instance would require a program. C Sharp (programming language)_sentence_145

To avoid that irresolvable circular dependency, C# compilers processing console applications (like that above) report an error if there is no static Main method. C Sharp (programming language)_sentence_146

The void keyword declares that Main has no return value. C Sharp (programming language)_sentence_147

This line writes the output. C Sharp (programming language)_sentence_148

Console is a static class in the System namespace. C Sharp (programming language)_sentence_149

It provides an interface to the standard input, output, and error streams for console applications. C Sharp (programming language)_sentence_150

The program calls the Console method WriteLine, which displays on the console a line with the argument, the string "Hello, world! C Sharp (programming language)_sentence_151

". C Sharp (programming language)_sentence_152

GUI C Sharp (programming language)_section_35

A GUI example: C Sharp (programming language)_sentence_153

This example is similar to the previous example, except that it generates a dialog box that contains the message "Hello, World!" C Sharp (programming language)_sentence_154

instead of writing it to the console. C Sharp (programming language)_sentence_155

Images C Sharp (programming language)_section_36

Another useful library is the System.Drawing library, which is used to programmatically draw images. C Sharp (programming language)_sentence_156

For example: C Sharp (programming language)_sentence_157

This will create an image that is identical to that stored in "Image.png". C Sharp (programming language)_sentence_158

Standardization and licensing C Sharp (programming language)_section_37

In August 2001, 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. C Sharp (programming language)_sentence_159

In December 2001, ECMA released ECMA-334 C# Language Specification. C Sharp (programming language)_sentence_160

C# became an ISO standard in 2003 (ISO/IEC 23270:2003 - Information technology — Programming languages — C#). C Sharp (programming language)_sentence_161

ECMA had previously adopted equivalent specifications as the 2nd edition of C#, in December 2002. C Sharp (programming language)_sentence_162

In June 2005, ECMA approved edition 3 of the C# specification, and updated ECMA-334. C Sharp (programming language)_sentence_163

Additions included partial classes, anonymous methods, nullable types, and generics (somewhat similar to C++ templates). C Sharp (programming language)_sentence_164

In July 2005, ECMA submitted to ISO/IEC JTC 1, via the latter's Fast-Track process, the standards and related TRs. C Sharp (programming language)_sentence_165

This process usually takes 6–9 months. C Sharp (programming language)_sentence_166

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. C Sharp (programming language)_sentence_167

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. C Sharp (programming language)_sentence_168

Microsoft has also agreed not to enforce patents relating to Novell products against Novell's paying customers with the exception of a list of products that do not explicitly mention C#, .NET or Novell's implementation of .NET (The Mono Project). C Sharp (programming language)_sentence_169

However, Novell maintains that Mono does not infringe any Microsoft patents. C Sharp (programming language)_sentence_170

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. C Sharp (programming language)_sentence_171

Implementations C Sharp (programming language)_section_38

Microsoft is leading the development of the open-source reference C# compilers and set of tools, the first compiler Roslyn compiles into intermediate language (IL), the second one RyuJIT, is a JIT (just-in-time) compiler, which is dynamic and does on-the-fly optimization and compiles the IL into native code for the front-end of the CPU. C Sharp (programming language)_sentence_172

RuyJIT is open source and written in c++. C Sharp (programming language)_sentence_173

Roslyn is entirely written in managed code (C#), has been opened up and functionality surfaced as APIs. C Sharp (programming language)_sentence_174

It is thus enabling developers to create refactoring and diagnostics tools. C Sharp (programming language)_sentence_175

Two branches of official implementation are the .NET (closed sources, Windows 10 only since .NET 4.6.2) and the .NET core (open source, multiplatform); .NET and .NET core are converging into one open source implementation .NET 5.0. C Sharp (programming language)_sentence_176

At .NET 4.6 a new JIT compiler replaced the former. C Sharp (programming language)_sentence_177

Other C# compilers (some of which include an implementation of the Common Language Infrastructure and .NET class libraries): C Sharp (programming language)_sentence_178

C Sharp (programming language)_unordered_list_3

  • The Mono project provides an open-source C# compiler, a complete open-source implementation of the Common Language Infrastructure including the required framework libraries as they appear in the ECMA specification, and a nearly complete implementation of the Microsoft proprietary .NET class libraries up to .NET 3.5. As of Mono 2.6, no plans exist to implement WPF; WF is planned for a later release; and there are only partial implementations of LINQ to SQL and WCF.C Sharp (programming language)_item_3_13
  • The Elements tool chain from RemObjects includes RemObjects C#, which compiles C# for .NET, Java, Cocoa, Android, Windows, Linux and WebAssembly.* The DotGNU project (now discontinued) also provided an open-source C# compiler, a nearly complete implementation of the Common Language Infrastructure including the required framework libraries as they appear in the ECMA specification, and subset of some of the remaining Microsoft proprietary .NET class libraries up to .NET 2.0 (those not documented or included in the ECMA specification, but included in Microsoft's standard .NET Framework distribution).C Sharp (programming language)_item_3_14
  • Xamarin provides tools to develop cross-platform applications for common mobile and desktop operating systems, using C# as a codebase and compiling to native code.C Sharp (programming language)_item_3_15

Mono is a common choice for game engines due to its cross-platform nature. C Sharp (programming language)_sentence_179

The Unity game engine uses Mono C# as its primary scripting language. C Sharp (programming language)_sentence_180

The Godot game engine has implemented an optional Mono C# module thanks to a donation of $24,000 from Microsoft. C Sharp (programming language)_sentence_181

See also C Sharp (programming language)_section_39

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/C Sharp (programming language).