introduction to c# raimonds rudmanis senior consultant microsoft baltic
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Introduction to C#Introduction to C#
Raimonds RudmanisRaimonds RudmanisSenior ConsultantSenior ConsultantMicrosoft Microsoft BalticBaltic
Session PrerequisitesSession Prerequisites
This session assumes that you This session assumes that you understand the fundamentals ofunderstand the fundamentals of Object oriented programming Object oriented programming
This is a Level 200 SessionThis is a Level 200 Session
What Will Be Covered TodayWhat Will Be Covered Today
Brief introduction to Brief introduction to the .NET frameworkthe .NET framework
C# language overviewC# language overview
AgendaAgenda
Hello WorldHello World The .NET FrameworkThe .NET Framework Design Goals of C#Design Goals of C# Language FeaturesLanguage Features
Hello WorldHello WorldDEMO 1: Hello WorldDEMO 1: Hello World
using System;using System;
class Helloclass Hello{{ static void Main() {static void Main() { Console.WriteLine("Hello world");Console.WriteLine("Hello world"); }}}}
AgendaAgenda
Hello WorldHello World The .NET FrameworkThe .NET Framework Design Goals of C#Design Goals of C# Language FeaturesLanguage Features
The .NET FrameworkThe .NET FrameworkOverviewOverview
Base Class LibraryBase Class Library
Common Language SpecificationCommon Language Specification
Common Language RuntimeCommon Language Runtime
ADO.NET: Data and XMLADO.NET: Data and XML
VBVB C++C++ C#C#
Visu
al Stu
dio
.NE
TV
isual S
tud
io.N
ET
ASP.NET: Web ServicesASP.NET: Web ServicesAnd Web FormsAnd Web Forms
JScriptJScript ……
WindowsWindowsformsforms
The .NET FrameworkThe .NET FrameworkCommon Language RuntimeCommon Language Runtime
Base Class LibraryBase Class Library
Common Language SpecificationCommon Language Specification
Common Language RuntimeCommon Language Runtime
ADO.NET: Data and XMLADO.NET: Data and XML
VBVB C++C++ C#C#V
isual S
tud
io.N
ET
Visu
al Stu
dio
.NE
T
ASP.NET: Web ServicesASP.NET: Web Servicesand Web Formsand Web Forms
JScriptJScript ……
WindowsWindowsFormsForms
New Runtime Environment – Common New Runtime Environment – Common Language RuntimeLanguage Runtime Language InteroperabilityLanguage Interoperability Common Classes for all LanguagesCommon Classes for all Languages Common Types for all LanguagesCommon Types for all Languages Runtime Controls Compilation to Machine Runtime Controls Compilation to Machine
CodeCode AssembliesAssemblies Application DomainsApplication Domains
The .NET FrameworkThe .NET FrameworkCommon Language RuntimeCommon Language Runtime
The .NET FrameworkThe .NET FrameworkCommon Language RuntimeCommon Language Runtime
Simplified developmentSimplified development XCOPY deploymentXCOPY deployment ScalabilityScalability Rich Web clients and safe Web hostingRich Web clients and safe Web hosting Potentially multi-platformPotentially multi-platform Multiple languages (cross inheritance)Multiple languages (cross inheritance) Increases productivityIncreases productivity Robust and secure execution environmentRobust and secure execution environment
.NET Framework and CLR .NET Framework and CLR CLR Execution ModelCLR Execution Model
VBVBSource Source codecode
CompilerCompiler
C++C++C#C#
CompilerCompilerCompilerCompiler
AssemblyAssemblyIL CodeIL Code
AssemblyAssemblyIL CodeIL Code
AssemblyAssemblyIL CodeIL Code
Operating System ServicesOperating System Services
Common Language RuntimeCommon Language Runtime
JIT CompilerJIT Compiler
Native CodeNative Code
ManagedManagedcodecode
UnmanagedUnmanagedComponentComponent
The .NET FrameworkThe .NET Framework.NET Framework Services.NET Framework Services
Base Class LibraryBase Class Library
Common Language SpecificationCommon Language Specification
Common Language RuntimeCommon Language Runtime
ADO.NET: Data and XMLADO.NET: Data and XML
VBVB C++C++ C#C#V
isual S
tud
io.N
ET
Visu
al Stu
dio
.NE
T
ASP.NET: Web ServicesASP.NET: Web Servicesand Web Formsand Web Forms
JScriptJScript ……
WindowsWindowsFormsForms
The .NET FrameworkThe .NET Framework.NET Framework Services.NET Framework Services
ASP.NETASP.NET Separation of code and presentationSeparation of code and presentation CompiledCompiled Web Forms Web Forms Web ServicesWeb Services
WindowsWindows®® Forms Forms Framework for building rich clientsFramework for building rich clients
ADO.NET, Evolution of ADOADO.NET, Evolution of ADO New objects (e.g., DataSets)New objects (e.g., DataSets)
XML support throughoutXML support throughout
AgendaAgenda
Hello WorldHello World The .NET FrameworkThe .NET Framework Design Goals of C#Design Goals of C# Language FeaturesLanguage Features
Design Goals of C#Design Goals of C#The Big IdeasThe Big Ideas
The first The first “C“Component omponent OOrientedriented”” language in the C/C++ familylanguage in the C/C++ family
Everything really is an objectEverything really is an object Next generation robust and Next generation robust and
durable softwaredurable software Preserving your investmentPreserving your investment
Design Goals of C#Design Goals of C# A Component Oriented LanguageA Component Oriented Language
C# is the first “Component Oriented” C# is the first “Component Oriented” language in the C/C++ familylanguage in the C/C++ family
Component concepts are first classComponent concepts are first class Properties, methods, eventsProperties, methods, events Design-time and run-time attributesDesign-time and run-time attributes Integrated documentation using XMLIntegrated documentation using XML
Enables one-stop programmingEnables one-stop programming No No external files like external files like header files, IDL, etc.header files, IDL, etc. Can be embedded in ASP pagesCan be embedded in ASP pages
Design Goals of C#Design Goals of C# Everything Really Is an ObjectEverything Really Is an Object
Traditional viewsTraditional views C++, JavaC++, Java™™: Primitive types are “magic” : Primitive types are “magic”
and do not interoperate with objectsand do not interoperate with objects Smalltalk, Lisp: Primitive types are Smalltalk, Lisp: Primitive types are
objects, but at great performance costobjects, but at great performance cost C# unifies with no performance costC# unifies with no performance cost
Deep simplicity throughout systemDeep simplicity throughout system Improved extensibility and reusabilityImproved extensibility and reusability
New primitive types: Decimal, SQL…New primitive types: Decimal, SQL… Collections, etc., work for all typesCollections, etc., work for all types
Design Goals of C#Design Goals of C# Robust and Durable SoftwareRobust and Durable Software
Garbage collectionGarbage collection No memory leaks and stray pointersNo memory leaks and stray pointers
ExceptionsExceptions Error handling is not an afterthoughtError handling is not an afterthought
Type-safetyType-safety No uninitialized variables, unsafe castsNo uninitialized variables, unsafe casts
VersioningVersioning Pervasive versioning considerations in all Pervasive versioning considerations in all
aspects of language designaspects of language design
Design Goals of C#Design Goals of C# Preserving Your InvestmentPreserving Your Investment C++ HeritageC++ Heritage
Namespaces, Namespaces, enums, enums, pointers (in unsafe pointers (in unsafe code), unsigned types, etc.code), unsigned types, etc.
No unnecessary sacrificesNo unnecessary sacrifices Real-world useful constructsReal-world useful constructs
foreach, using, switch on stringforeach, using, switch on string decimal type for financial applicationsdecimal type for financial applications ref and out parametersref and out parameters
Millions of lines of C# code in .NETMillions of lines of C# code in .NET Short learning curveShort learning curve Increased productivityIncreased productivity
Design Goals of C#Design Goals of C# InteroperabilityInteroperability
C#C#
VB.NETVB.NET
MC++MC++
JScript JScript
... ...
.NET Languages.NET Languages
COMCOMOLE AutomationOLE Automation
XML/SOAPXML/SOAP
Dynamic Link LibrariesDynamic Link Libraries
P/Invoke and unsafe codeP/Invoke and unsafe code
AgendaAgenda
Hello WorldHello World The .NET FrameworkThe .NET Framework Design Goals of C#Design Goals of C# Language FeaturesLanguage Features
Language FeaturesLanguage FeaturesProgram StructureProgram Structure
NamespacesNamespaces Contain types and other namespacesContain types and other namespaces
Type declarationsType declarations Classes, structs, interfaces, enums, Classes, structs, interfaces, enums,
and delegatesand delegates MembersMembers
Constants, fields, methods, properties, indexers, Constants, fields, methods, properties, indexers, events, operators, constructors, destructorsevents, operators, constructors, destructors
OrganizationOrganization No header files, code written “in-line”No header files, code written “in-line” No declaration order dependenceNo declaration order dependence
Language FeaturesLanguage Features Program StructureProgram Structure
using System;using System;
namespace System.Collectionsnamespace System.Collections
{{
public class Stackpublic class Stack
{{
Entry top;Entry top;
public void Push(object data) {public void Push(object data) {
top = new Entry(top, data);top = new Entry(top, data);
}}
public object Pop() {public object Pop() {
if (top == null) throw new InvalidOperationException();if (top == null) throw new InvalidOperationException();
object result = top.data;object result = top.data;
top = top.next;top = top.next;
return result;return result;
}}
}}
}}
Language FeaturesLanguage Features Type SystemType System
Value typesValue types Directly contain dataDirectly contain data Cannot be nullCannot be null
Reference typesReference types Contain references to objectsContain references to objects May be nullMay be null
int i = 123;int i = 123;string s = "Hello world";string s = "Hello world";
123123ii
ss "Hello world""Hello world"
Language FeaturesLanguage Features Type SystemType System
Value typesValue types PrimitivesPrimitives int i;int i; EnumsEnums enum State { Off, On }enum State { Off, On } StructsStructs struct Point { int x, struct Point { int x,
y; }y; } Reference typesReference types
ClassesClasses class Foo: Bar, IFoo class Foo: Bar, IFoo {...}{...}
InterfacesInterfaces interface IFoo: IBar interface IFoo: IBar {...}{...}
ArraysArrays string[] a = new string[] a = new string[10];string[10];
DelegatesDelegates delegate void delegate void Empty();Empty();
Language FeaturesLanguage Features Predefined TypesPredefined Types
C# predefined typesC# predefined types ReferenceReference object, stringobject, string SignedSigned sbyte, short, int, sbyte, short, int,
longlong Unsigned Unsigned byte, ushort, uint, byte, ushort, uint,
ulongulong CharacterCharacter charchar Floating-pointFloating-point float, double, float, double,
decimaldecimal LogicalLogical boolbool
Predefined types are simply aliases for Predefined types are simply aliases for system-provided typessystem-provided types For example, int = System.Int32For example, int = System.Int32
Language FeaturesLanguage Features ClassesClasses
Single inheritanceSingle inheritance Multiple interface implementationMultiple interface implementation Class membersClass members
Constants, fields, methods, Constants, fields, methods, properties, indexers, events, properties, indexers, events, operators, constructors, destructorsoperators, constructors, destructors
Static and instance membersStatic and instance members Nested typesNested types
Member accessMember access Public, protected, internal, privatePublic, protected, internal, private
Language FeaturesLanguage Features StructsStructs
Like classes, exceptLike classes, except Stored in-line, not heap allocatedStored in-line, not heap allocated Assignment copies data, not referenceAssignment copies data, not reference No inheritanceNo inheritance
Ideal for light weight objectsIdeal for light weight objects Complex, point, rectangle, colorComplex, point, rectangle, color int, float, double, etc., are all structsint, float, double, etc., are all structs
BenefitsBenefits No heap allocation, less GC pressureNo heap allocation, less GC pressure More efficient use of memoryMore efficient use of memory
Language FeaturesLanguage Features Classes and StructsClasses and Structs
struct SPoint { int x, y; ... }struct SPoint { int x, y; ... } class CPoint { int x, y; ... }class CPoint { int x, y; ... }
SPoint sp = new SPoint(10, 20);SPoint sp = new SPoint(10, 20);CPoint cp = new CPoint(10, 20);CPoint cp = new CPoint(10, 20);
1010
2020spsp
cpcp
1010
2020
CPointCPoint
Language FeaturesLanguage Features InterfacesInterfaces
Multiple inheritanceMultiple inheritance Can contain methods, properties, Can contain methods, properties,
indexers and eventsindexers and events Private interface implementationsPrivate interface implementations
interface IDataBoundinterface IDataBound{{ void Bind(IDataBinder binder);void Bind(IDataBinder binder);}}
class EditBox: Control, IDataBoundclass EditBox: Control, IDataBound{{ void IDataBound.Bind(IDataBinder binder) {...}void IDataBound.Bind(IDataBinder binder) {...}}}
Language FeaturesLanguage Features EnumsEnums
Strongly typedStrongly typed No implicit conversions to/from intNo implicit conversions to/from int Operators: +, -, ++, --, &, |, ^, ~Operators: +, -, ++, --, &, |, ^, ~
Can specify underlying typeCan specify underlying type Byte, short, int, longByte, short, int, long
enum Color: byteenum Color: byte{{ Red = 1,Red = 1, Green = 2,Green = 2, Blue = 4,Blue = 4, Black = 0,Black = 0, White = Red | Green | Blue,White = Red | Green | Blue,}}
Language FeaturesLanguage Features DelegatesDelegates
Object oriented function pointersObject oriented function pointers Multiple receiversMultiple receivers
Each delegate has an invocation listEach delegate has an invocation list Thread-safe + and - operationsThread-safe + and - operations
Foundation for framework eventsFoundation for framework events
delegate void MouseEvent(int x, int y);delegate void MouseEvent(int x, int y);
delegate double Func(double x);delegate double Func(double x);
Func func = new Func(Math.Sin);Func func = new Func(Math.Sin);double x = func(1.0);double x = func(1.0);
Language FeaturesLanguage FeaturesUnified Type SystemUnified Type System
Everything is an objectEverything is an object All types ultimately inherit from objectAll types ultimately inherit from object Any piece of data can be stored, Any piece of data can be stored,
transported, and manipulated with no transported, and manipulated with no extra workextra work
StreamStream
MemoryStreamMemoryStream FileStreamFileStream
HashtableHashtable doubledoubleintint
objectobject
Language FeaturesLanguage FeaturesUnified Type SystemUnified Type System
BoxingBoxing Allocates box, copies value into itAllocates box, copies value into it
UnboxingUnboxing Checks type of box, copies value outChecks type of box, copies value out
int i = 123;int i = 123;object o = i;object o = i;int j = (int)o;int j = (int)o;
123123i
o
123123
System.Int32System.Int32
123123j
Language FeaturesLanguage FeaturesUnified Type SystemUnified Type System
BenefitsBenefits Eliminates “wrapper classes”Eliminates “wrapper classes” Collection classes work with all typesCollection classes work with all types Replaces OLE Automation's VariantReplaces OLE Automation's Variant
Lots of examples in .NET frameworkLots of examples in .NET framework
string s = string.Format(string s = string.Format( "Your total was {0} on {1}", total, date);"Your total was {0} on {1}", total, date);
ArrayList al = new ArrayList();ArrayList al = new ArrayList();
al.Add( new Customer() );al.Add( new Customer() );al.Add( 1 );al.Add( 1 );al.Add( "test" );al.Add( "test" );
Language FeaturesLanguage FeaturesComponent DevelopmentComponent Development
What defines a component?What defines a component? Properties, methods, eventsProperties, methods, events Integrated help and documentationIntegrated help and documentation Design-time informationDesign-time information
C# has first class supportC# has first class support Not naming patterns, adapters, etc.Not naming patterns, adapters, etc. Not external filesNot external files
Components are easy to build and Components are easy to build and to consumeto consume
Language FeaturesLanguage Features PropertiesProperties
Properties Are “Smart Fields”Properties Are “Smart Fields” Natural syntax, accessors, inliningNatural syntax, accessors, inlining
public class Button: Controlpublic class Button: Control{{ private string caption;private string caption;
public string Caption {public string Caption { get {get { return caption;return caption; }} set {set { caption = value;caption = value; Repaint();Repaint(); }} }}}}
Button b = new Button();Button b = new Button();b.Caption = "OK";b.Caption = "OK";String s = b.Caption;String s = b.Caption;
Language FeaturesLanguage Features IndexersIndexers
Indexers are “smart arrays”Indexers are “smart arrays” Can be overloadedCan be overloaded
public class ListBox: Controlpublic class ListBox: Control{{ private string[] items;private string[] items;
public string this[int public string this[int index] {index] { get {get { return items[index];return items[index]; }} set {set { items[index] = value; items[index] = value; Repaint();Repaint(); }} }}}}
ListBox listBox = new ListBox listBox = new ListBox();ListBox();listBox[0] = "hello";listBox[0] = "hello";Console.WriteLine(listBox[0]);Console.WriteLine(listBox[0]);
Language FeaturesLanguage Features Creating and Firing an EventCreating and Firing an Event
Define the Event signatureDefine the Event signature
Define the Event and firing logicDefine the Event and firing logic
public delegate void EventHandler(object sender, public delegate void EventHandler(object sender, EventArgs e);EventArgs e);
public class Buttonpublic class Button{{ public event EventHandler Click; public event EventHandler Click;
protected void OnClick(EventArgs e) {protected void OnClick(EventArgs e) { if (Click != null) Click(this, e); if (Click != null) Click(this, e); } }}}
Language FeaturesLanguage Features Handling an EventHandling an Event
Define and register Event HandlerDefine and register Event Handler
public class MyForm: Formpublic class MyForm: Form{{ Button okButton;Button okButton;
public MyForm() {public MyForm() { okButton = new Button(...);okButton = new Button(...); okButton.Caption = "OK";okButton.Caption = "OK"; okButton.Click +=okButton.Click += new EventHandler(OkButtonClick); new EventHandler(OkButtonClick); }}
void OkButtonClick(object sender, EventArgs e) {void OkButtonClick(object sender, EventArgs e) { ShowMessage("You pressed the OK button");ShowMessage("You pressed the OK button"); }}}}
Language FeaturesLanguage FeaturesDEMO 2: Creating an Event HandlerDEMO 2: Creating an Event Handler Define an Event Handler for a button in a Define an Event Handler for a button in a
Windows Forms applicationWindows Forms application
Language FeaturesLanguage Features AttributesAttributes
Associate information with types Associate information with types and membersand members Documentation URL for a classDocumentation URL for a class Transaction context for a methodTransaction context for a method XML persistence mappingXML persistence mapping
Traditional solutionsTraditional solutions Add keywords or pragmas to languageAdd keywords or pragmas to language Use external files, e.g., .IDL, .DEFUse external files, e.g., .IDL, .DEF
C# solution: AttributesC# solution: Attributes
Language FeaturesLanguage Features AttributesAttributes
public class OrderProcessorpublic class OrderProcessor{{ [WebMethod][WebMethod] public void SubmitOrder(PurchaseOrder order) {...}public void SubmitOrder(PurchaseOrder order) {...}}}
[XmlRoot("Order", Namespace="urn:acme.b2b-schema.v1")][XmlRoot("Order", Namespace="urn:acme.b2b-schema.v1")]public class PurchaseOrderpublic class PurchaseOrder{{ [XmlElement("shipTo")] public Address ShipTo;[XmlElement("shipTo")] public Address ShipTo; [XmlElement("billTo")] public Address BillTo;[XmlElement("billTo")] public Address BillTo; [XmlElement("comment")] public string Comment;[XmlElement("comment")] public string Comment; [XmlElement("items")] public Item[] Items;[XmlElement("items")] public Item[] Items; [XmlAttribute("date")] public DateTime OrderDate;[XmlAttribute("date")] public DateTime OrderDate;}}
public class Address {...}public class Address {...}
public class Item {...}public class Item {...}
Language FeaturesLanguage Features AttributesAttributes
Attributes can beAttributes can be Attached to types and membersAttached to types and members Examined at run-time using reflectionExamined at run-time using reflection
Completely extensibleCompletely extensible Simply a class that inherits from System.AttributeSimply a class that inherits from System.Attribute
Type-safeType-safe Arguments checked at compile-timeArguments checked at compile-time
Extensive use in .NET frameworkExtensive use in .NET framework XML, Web Services, security, serialization, XML, Web Services, security, serialization,
component model, COM and P/Invoke interop, component model, COM and P/Invoke interop, code configuration…code configuration…
What Is A Web Service?What Is A Web Service?
HTML = user-to-machineHTML = user-to-machineXML/SOAP = machine-to-machineXML/SOAP = machine-to-machineLeveraging the WebLeveraging the Web
Same infrastructureSame infrastructure Same programming modelSame programming model Anyone can playAnyone can play
Truly scalable distributed applicationsTruly scalable distributed applications Stateless and loosely coupledStateless and loosely coupled Both Internet and intranetBoth Internet and intranet
DiscoveryDiscovery
Let’s talk (SOAP)Let’s talk (SOAP)
How Does It Work?How Does It Work?
http://myservice.comhttp://myservice.com
HTML or XML with link to WSDLHTML or XML with link to WSDL
How do we talk? (WSDL)How do we talk? (WSDL)http://myservice.com?wsdlhttp://myservice.com?wsdl
XML with service descriptionsXML with service descriptions
http://myservice.com/svc1http://myservice.com/svc1
XML/SOAP BODYXML/SOAP BODY
Web Web ServiceService
WebWebService Service
ConsumerConsumer
UDDIUDDI
Find a ServiceFind a Servicehttp://www.uddi.orghttp://www.uddi.org
Link to DISCO or WSDL documentLink to DISCO or WSDL document
Web Services With .NETWeb Services With .NET
ProgramsPrograms
ObjectsObjects
ClassesClasses
MethodsMethods
CallsCalls
WebWeb
XMLXML
XSDXSD
WSDLWSDL
SOAPSOAP
DataData
SchemaSchema
ServicesServices
InvocationInvocation
ApplicationApplicationConceptsConcepts
The .NET framework providesThe .NET framework providesa bi-directional mappinga bi-directional mapping
Web Services With .NETWeb Services With .NETpublic class OrderProcessorpublic class OrderProcessor{{
public void SubmitOrder(PurchaseOrder order) {...}public void SubmitOrder(PurchaseOrder order) {...}}}
public class PurchaseOrderpublic class PurchaseOrder{{ public string ShipTo;public string ShipTo; public string BillTo;public string BillTo; public string Comment;public string Comment; public Item[] Items;public Item[] Items; public DateTime OrderDate;public DateTime OrderDate;}}
public class OrderProcessorpublic class OrderProcessor{{ [WebMethod][WebMethod] public void SubmitOrder(PurchaseOrder order) {...}public void SubmitOrder(PurchaseOrder order) {...}}}
[XmlRoot("Order", Namespace="urn:acme.b2b-schema.v1")][XmlRoot("Order", Namespace="urn:acme.b2b-schema.v1")]public class PurchaseOrderpublic class PurchaseOrder{{ [XmlElement("shipTo")][XmlElement("shipTo")] public string ShipTo; public string ShipTo; [XmlElement("billTo")][XmlElement("billTo")] public string BillTo; public string BillTo; [XmlElement("comment")][XmlElement("comment")] public string Comment; public string Comment; [XmlElement("items")][XmlElement("items")] public Item[] Items; public Item[] Items; [XmlAttribute("date")][XmlAttribute("date")] public DateTime OrderDate; public DateTime OrderDate;}}
PurchaseOrder po = new PurchaseOrder();PurchaseOrder po = new PurchaseOrder();po.ShipTo = “Anders Hejlsberg";po.ShipTo = “Anders Hejlsberg";po.BillTo = “Bill Gates";po.BillTo = “Bill Gates";po.OrderDate = DateTime.Today;po.OrderDate = DateTime.Today;……OrderProcessor.SubmitOrder(po);OrderProcessor.SubmitOrder(po);
<?xml version="1.0" encoding="utf-8"?><?xml version="1.0" encoding="utf-8"?><soap:Envelope><soap:Envelope> <soap:Body><soap:Body> <SubmitOrder><SubmitOrder> <Order date=“20010703"><Order date=“20010703"> <shipTo>Anders Hejlsberg</shipTo><shipTo>Anders Hejlsberg</shipTo> <billTo>Bill Gates</billTo><billTo>Bill Gates</billTo> <comment>Overnight delivery</comment><comment>Overnight delivery</comment> <items><items> <productId>17748933</productId><productId>17748933</productId> <description>Dom Perignon</description><description>Dom Perignon</description> </items></items> </Order></Order> </SubmitOrder></SubmitOrder> </soap:Body></soap:Body></soap:Envelope></soap:Envelope>
Language FeaturesLanguage FeaturesDEMO 3: AttributesDEMO 3: Attributes Create a Web service by using the Create a Web service by using the
[[WWebebMMethod] attributeethod] attribute
Language FeaturesLanguage Features XML CommentsXML Comments
class XmlElementclass XmlElement{{ /// <summary>/// <summary> /// Returns the attribute with the given name and/// Returns the attribute with the given name and /// namespace</summary>/// namespace</summary> /// <param name="name">/// <param name="name"> /// The name of the attribute</param>/// The name of the attribute</param> /// <param name="ns">/// <param name="ns"> /// The namespace of the attribute, or null if/// The namespace of the attribute, or null if /// the attribute has no namespace</param>/// the attribute has no namespace</param> /// <return>/// <return> /// The attribute value, or null if the attribute/// The attribute value, or null if the attribute /// does not exist</return>/// does not exist</return> /// <seealso cref="GetAttr(string)"/>/// <seealso cref="GetAttr(string)"/> ////// public string GetAttr(string name, string ns) {public string GetAttr(string name, string ns) { ...... }}}}
Language FeaturesLanguage FeaturesDEMO 4: XML CommentsDEMO 4: XML Comments Show how the compiler can auto generate Show how the compiler can auto generate
documentation from the source code using documentation from the source code using XML commentsXML comments
Language FeaturesLanguage FeaturesStatements and ExpressionsStatements and Expressions
High C++ fidelityHigh C++ fidelity if, while, do require bool conditionif, while, do require bool condition Switch statementSwitch statement
No fall-through, “goto case” or “goto default”No fall-through, “goto case” or “goto default” Goto can’t jump into blocksGoto can’t jump into blocks Foreach statementForeach statement Checked and Checked and
uncheckeduncheckedstatementsstatements
Expression Expression statements statements must do workmust do work
void Foo() {void Foo() {i == 1;i == 1; // error// errori + j;i + j; // error// error
}}
switch( arg )switch( arg ){{ case 0:case 0: case 1: case 1: Console.WriteLine(“Low”);Console.WriteLine(“Low”); case 2:case 2: Console.WriteLine(“Med”);Console.WriteLine(“Med”); break;break; default:default:
Console.WriteLine(“High”);Console.WriteLine(“High”);}}
switch( arg )switch( arg ){{ case 0:case 0: case 1: case 1: Console.WriteLine(“Low”);Console.WriteLine(“Low”); break;break; case 2:case 2: Console.WriteLine(“Med”);Console.WriteLine(“Med”); break;break; default:default:
Console.WriteLine(“High”);Console.WriteLine(“High”);}}
switch( arg )switch( arg ){{ case 0:case 0: case 1: case 1: Console.WriteLine(“Low”);Console.WriteLine(“Low”); goto case 2;goto case 2; case 2:case 2: Console.WriteLine(“Med”);Console.WriteLine(“Med”); break;break; default:default:
Console.WriteLine(“High”);Console.WriteLine(“High”);}}
int i;int i;
if ( i ) // if ( i ) // errorerrorif ( i>0 )if ( i>0 )
FileClass file;FileClass file;
if ( file = OpenFile() ) // if ( file = OpenFile() ) // errorerrorif ( (file = OpenFile()) != NULL )if ( (file = OpenFile()) != NULL )
foreach ( string word in myArray.words )foreach ( string word in myArray.words ){{
Console.WriteLine(“{0}”, word)Console.WriteLine(“{0}”, word)}}
static short x = 32767; // Max shortstatic short x = 32767; // Max shortstatic short y = 32767;static short y = 32767;
try try {{z = z = checkedchecked((short)(x + y));((short)(x + y));}}
catch (OverflowException e) catch (OverflowException e) {{Console.WriteLine(e.ToString());Console.WriteLine(e.ToString());}}
goto in_label;goto in_label;while ( i<100 )while ( i<100 ){{in_label:in_label:
i++;i++;}}
while ( i<100 )while ( i<100 ){{if ( j>50 )if ( j>50 )
goto out_label;goto out_label;}}out_label:out_label:
Language FeaturesLanguage Features For Each StatementFor Each Statement
Iteration of arraysIteration of arrays
Iteration of user-defined collectionsIteration of user-defined collections
foreach (Customer c in customers.OrderBy("name")) {foreach (Customer c in customers.OrderBy("name")) { if (c.Orders.Count != 0) {if (c.Orders.Count != 0) { ...... }}}}
public static void Main(string[] args) {public static void Main(string[] args) { foreach (string s in args) Console.WriteLine(s);foreach (string s in args) Console.WriteLine(s);}}
Language FeaturesLanguage Features Parameter ArraysParameter Arrays
Can write “printf” style methodsCan write “printf” style methods Type-safe, unlike C++Type-safe, unlike C++
void printf(string fmt, params object[] args) {void printf(string fmt, params object[] args) { foreach (object x in args) {foreach (object x in args) { ...... }}}}
printf("%s %i %i", str, int1, int2);printf("%s %i %i", str, int1, int2);
object[] args = new object[3];object[] args = new object[3];args[0] = str;args[0] = str;args[1] = int1;args[1] = int1;Args[2] = int2;Args[2] = int2;printf("%s %i %i", args);printf("%s %i %i", args);
Language FeaturesLanguage Features Operator OverloadingOperator Overloading
First class user-defined data typesFirst class user-defined data types Used in base class libraryUsed in base class library
Decimal, DateTime, TimeSpanDecimal, DateTime, TimeSpan
Used in the frameworkUsed in the framework Unit, point, rectangleUnit, point, rectangle
Used in SQL integrationUsed in SQL integration SQLString, SQLInt16, SQLInt32, SQLString, SQLInt16, SQLInt32,
SQLInt64, SQLBool, SQLMoney, SQLInt64, SQLBool, SQLMoney, SQLNumeric, SQLFloat…SQLNumeric, SQLFloat…
Language FeaturesLanguage Features Operator OverloadingOperator Overloading
public struct DBIntpublic struct DBInt{{ public static readonly DBInt Null = new DBInt();public static readonly DBInt Null = new DBInt();
private int value;private int value; private bool defined;private bool defined;
public bool IsNull { get { return !defined; } }public bool IsNull { get { return !defined; } }
public static DBInt operator +(DBInt x, DBInt y) public static DBInt operator +(DBInt x, DBInt y) {...}{...}
public static implicit operator DBInt(int x) {...}public static implicit operator DBInt(int x) {...} public static explicit operator int(DBInt x) {...}public static explicit operator int(DBInt x) {...}}}
DBInt x = 123;DBInt x = 123;DBInt y = DBInt.Null;DBInt y = DBInt.Null;DBInt z = x + y;DBInt z = x + y;
Language FeaturesLanguage Features VersioningVersioning
Overlooked in most languagesOverlooked in most languages C++ and Java produce fragile base classes C++ and Java produce fragile base classes Users unable to express versioning intentUsers unable to express versioning intent
C# allows intent to be expressedC# allows intent to be expressed Methods are not virtual by defaultMethods are not virtual by default C# keywords “virtual”, “override” and C# keywords “virtual”, “override” and
“new” provide context“new” provide context C# can't guarantee versioningC# can't guarantee versioning
Can enable (e.g., explicit override)Can enable (e.g., explicit override) Can encourage (e.g., smart defaults)Can encourage (e.g., smart defaults)
class Derived: Baseclass Derived: Base // version 1// version 1{{ public virtual void Foo() {public virtual void Foo() { Console.WriteLine("Derived.Foo"); Console.WriteLine("Derived.Foo"); }}}}
class Derived: Baseclass Derived: Base // version 2a// version 2a{{ new public virtual void Foo() {new public virtual void Foo() { Console.WriteLine("Derived.Foo"); Console.WriteLine("Derived.Foo"); }}}}
class Derived: Baseclass Derived: Base // version 2b// version 2b{{ public override void Foo() {public override void Foo() { base.Foo();base.Foo(); Console.WriteLine("Derived.Foo"); Console.WriteLine("Derived.Foo"); }}}}
class Baseclass Base // version 1// version 1{{}}
class Base class Base // version 2 // version 2 {{ public virtual void Foo() {public virtual void Foo() { Console.WriteLine("Base.Foo"); Console.WriteLine("Base.Foo"); }}}}
Language FeaturesLanguage Features VersioningVersioning
Language FeaturesLanguage Features Conditional CompilationConditional Compilation
#define, #undef#define, #undef #if, #elif, #else, #endif#if, #elif, #else, #endif
Simple boolean logicSimple boolean logic Conditional methodsConditional methods
public class Debugpublic class Debug{{ [Conditional("Debug")][Conditional("Debug")] public static void Assert(bool cond, String s) {public static void Assert(bool cond, String s) { if (!cond) {if (!cond) { throw new AssertionException(s);throw new AssertionException(s); }} }}}}
Language FeaturesLanguage Features Unsafe CodeUnsafe Code
COM integration, P/invoke cover most casesCOM integration, P/invoke cover most cases Unsafe codeUnsafe code
Low-level code without leaving the boxLow-level code without leaving the box Enables unsafe casts, pointer arithmeticEnables unsafe casts, pointer arithmetic
Declarative pinningDeclarative pinning Fixed statementFixed statement
Basically “inline C”Basically “inline C”
unsafe void Foo() {unsafe void Foo() { char* buf = stackalloc char[256];char* buf = stackalloc char[256]; for (char* p = buf; p < buf + 256; p++) *p = 0;for (char* p = buf; p < buf + 256; p++) *p = 0; ......}}
Language FeaturesLanguage Features Unsafe CodeUnsafe Code
class FileStream: Streamclass FileStream: Stream{{ int handle;int handle;
public public unsafeunsafe int Read(byte[] buffer, int index, int int Read(byte[] buffer, int index, int count) {count) { int n = 0;int n = 0; fixedfixed (byte* p = buffer) { (byte* p = buffer) { ReadFile(handle, p + index, count, &n, null);ReadFile(handle, p + index, count, &n, null); }} return n;return n; }}
[[dllimportdllimport("kernel32", SetLastError=true)]("kernel32", SetLastError=true)] static extern static extern unsafeunsafe bool ReadFile(int hFile, bool ReadFile(int hFile, void* lpBuffer, int nBytesToRead,void* lpBuffer, int nBytesToRead, int* nBytesRead, Overlapped* lpOverlapped);int* nBytesRead, Overlapped* lpOverlapped);}}
Language FeaturesLanguage FeaturesCOM SupportCOM Support
.Net framework provides great .Net framework provides great COM support COM support TLBIMP imports existing COM classesTLBIMP imports existing COM classes TLBEXP exports .NET types TLBEXP exports .NET types
Most users will have a Most users will have a seamless experienceseamless experience
Language FeaturesLanguage FeaturesCOM SupportCOM Support
Sometimes you need more control Sometimes you need more control Methods with complicated structures Methods with complicated structures
as argumentsas arguments Large TLB – only using a few classesLarge TLB – only using a few classes
System.Runtime.InteropservicesSystem.Runtime.Interopservices COM object identificationCOM object identification Parameter and return value marshallingParameter and return value marshalling HRESULT behaviorHRESULT behavior
Language FeaturesLanguage Features DEMO 5: COM and C#DEMO 5: COM and C#Call a COM component from C#Call a COM component from C#
Language FeaturesLanguage Features DEMO 6: Visual Studio .NETDEMO 6: Visual Studio .NETWindows programming with C#Windows programming with C#
C# And CLI StandardizationC# And CLI Standardization
Work begun in September 2000Work begun in September 2000Submitted to ECMA (www.ecma.ch)Submitted to ECMA (www.ecma.ch)Active involvement by Intel, HP, IBM, Active involvement by Intel, HP, IBM,
Fujitsu, Plum Hall, …Fujitsu, Plum Hall, …Since December 2001Since December 2001
““C# Language Specification”C# Language Specification” ““Common Language Infrastructure (CLI)”Common Language Infrastructure (CLI)”
C# BooksC# Books
C# CustomersC# Customers
More ResourcesMore Resources
http://msdn.microsoft.com/http://msdn.microsoft.com/ C# language specificationC# language specification C# newsgroupsC# newsgroups
microsoft.public.dotnet.languages.csharpmicrosoft.public.dotnet.languages.csharp
Questions?Questions?
© 2001 Microsoft Corporation. All rights reserved.© 2001 Microsoft Corporation. All rights reserved.
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