Dr archana dhawan bajaj - c# dot net

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Dr archana dhawan bajaj's Sales JetView.Dr archana dhawan bajaj is a renowned practising doctor of non-commercial of India and Dr archana various Hospitals and Meternity.Dr archana dhawan bajaj has a PH.d master's degree in both human & International client Management along with other fellow.Dr archana is known to be proficient in Hindi,English,Sanskrit and Urdu.Dr archana dhawan bajaj has acquired extensive practice experience in maternity primarily in relation to corporate and international matter delivery.Dr archana dhawan bajaj's Sales JetView.Dr archana dhawan bajaj is a renowned practising doctor of non-commercial of India and Dr archana various Hospitals and Meternity.Dr archana dhawan bajaj has a PH.d master's degree in both human & International client Management along with other fellow.Dr archana is known to be proficient in Hindi,English,Sanskrit and Urdu.Dr archana dhawan bajaj has acquired extensive practice experience in maternity primarily in relation to corporate and international matter delivery.Dr archana dhawan bajaj's Sales JetView.Dr archana dhawan bajaj is a renowned practising doctor of non-commercial of India and Dr archana various Hospitals and Meternity.Dr archana dhawan bajaj has a PH.d master's degree in both human & International client Management along with other fellow.Dr archana is known to be proficient in Hindi,English,Sanskrit and Urdu.Dr archana dhawan bajaj has acquired extensive practice experience in maternity primarily in relation to corporate and international matter delivery.Dr archana dhawan bajaj's Sales JetView.Dr archana dhawan bajaj is a renowned practising doctor of non-commercial of India and Dr archana various Hospitals and Meternity.Dr archana dhawan bajaj has a PH.d master's degree in both human & International client Management along with other fellow.Dr archana is known to be proficient in Hindi,English,Sanskrit and Urdu.Dr archana dhawan bajaj has acquired extensive practice experience in maternity primarily in relation to corporate and international matter delivery.Dr archana dhawan bajaj's Sales JetView.Dr archana dhawan bajaj is a renowned practising doctor of non-commercial of India and Dr archana various Hospitals and Meternity.Dr archana dhawan bajaj has a PH.d master's degree in both human & International client Management along with other fellow.Dr archana is known to be proficient in Hindi,English,Sanskrit and Urdu.Dr archana dhawan bajaj has acquired extensive practice experience in maternity primarily in relation to corporate and international matter delivery.Dr archana dhawan bajaj's Sales JetView.Dr archana dhawan bajaj is a renowned practising doctor of non-commercial of India and Dr archana various Hospitals and Meternity.Dr archana dhawan bajaj has a PH.d master's degree in both human & International client Management along with other fellow.Dr archana is known to be proficient in Hindi,English,Sanskrit and Urdu.Dr archana dhawan bajaj has acquired extensive practice exp

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Dr archana dhawan bajaj - c# dot net

  1. 1. 1 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. Operator Overloading 6. Event driven programming 7. .NET Framework Class Library 8. A GUI in C# 9. A web service in C#
  2. 2. 2 C# and .NET 1. Introduction • History • C# features • .NET framework 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. ...
  3. 3. 3 History Builds on legacy from • C/C++ tradition -> new programming language C# • Java tradition : many ideas borrowed • runtime environment : virtual machine • platform/language abstraction • guarded execution environment • garbage collection • single rooted hierarchy • ... Takes software development one step further towards component based design
  4. 4. 4 History procedural/structured design/programming object oriented design/programming component based design/programming C/PASCAL C++ JAVA C#/.NET component support possible BUT NOT built into the language - templates - deployment descriptors COM/COM+ CORBA component model
  5. 5. 5 C# features : component oriented Modern large-scale systems are component based Properties get/set event based communication support to annotate component for - deployment - configuration at design and/or runtime - component versioning - documentation
  6. 6. 6 C# features : OO paradigm supports all typical OO mechanisms • encapsulation • inheritance • polymorphism • interface based programming C++ legacy (NOT supported in Java) • support for operator overloading • user defined type conversions • rectangular arrays • pass-by-reference
  7. 7. 7 C# features : Excution model NO own runtime library - uses .NET library (redesign of MS-library) (implemented in C#) Compiles to intermediary language (CIL - Common Intermediate Language) Executed by virtual machine (CLR – Common Language Runtime) - memory management through garbage collection - guarded execution (e.g. array bounds guarding) - JIT compilation
  8. 8. 8 .NET framework “.NET framework” CLR FCL Framework Class Library Application Code Version 1.0 released January 15, 2002
  9. 9. 9 .NET execution model Platform AND language portability CLR can exploit processor/platform specific optimizations Supported languages : C#, J#, VB.NET, JScript, Microsoft IL, Managed Extensions for C++ Supplied by 3rd parties : COBOL, Eiffel, Haskell, Forth, Scheme, Smalltalk, Pascal, ... CLR Compiler Application Code in “A Language” CIL
  10. 10. 10 .NET : Common Type System Cross language type system, allowing - type safety - cross language integration - execution services (garbage collection, JIT, exceptions, ...) Defines rules to define types, irrespective of source language All types eventually mapped to CTS-types e.g. cross language inheritance J# class inherits from C# class Minimum subset for language to be supported by .NET : CLS – Common Language Specification - CLS-compliant language = “CLS consumer” - if more than CLS : “CLS extender” C#= both CLS consumer and extender
  11. 11. 11 .NET : FCL categories comprises - > 3500 classes - > 1 000 000 lines of code • core functions • basic datatypes, collections • IO (network, console, file) • calls to runtime services • database interaction • transactions • consuming/producing XML • manipulation of tables • web-based applications (thin clients) • desktop applications (thick clients) • SOAP-based XML web services
  12. 12. 12 Hello namespace Project1 { using System; class Class1 { static void Main() { Console.WriteLine("Hello there !"); for (int i = 0; i < 10; i++) Console.WriteLine(i); } } } package project1; import java.lang.*; class Class1 { public static void main(String[] args) { System.out.println("Hello there !"); for (int i = 0; i < 10; i++) System.out.println(i); } } C# Java
  13. 13. 13 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types
  14. 14. 14 C# - Java : common approaches Both intended as improvement to C++ • Compilation to machine independent language, managed execution • Garbage Collection, no pointers (C# allows pointer usage in special “unsafe” code sections) • Reflection API • No header files, no problems with circular (type) references • Single rooted hierarchy, objects allocated on the heap • Thread support by object-level lock • Multiple extension of interfaces, single inheritance for classes • Inner classes (closure instead of nested class) • Simple inheritance rules (no inheritance modifiers) • Everything is in a class (no global data, no global functions) • Arrays, strings : bounds checked at execution time • Systematic usage of “.” (instead of “->” and “::”) • Keywords for null pointer (null) and boolean type (boolean/bool) • Guaranteed initialization • if-statement controlled by boolean (instead of integer) • Finally-clause in try-catch blocks
  15. 15. 15 Properties C# : special support for getters/setters Java : implied by coding convention (template or “design pattern”) Property int min Java style : public int getMin() {return min;} public void setMin(int m) {min=m;} C# style : public int Min { get {return min;} set {min=value;} } // value : implicit variable used when // calling setter method - getter/setter grouped together - encourages to think in terms of properties
  16. 16. 16 IndexerMeans to index underlying datastructure Java style : public class Bookshop { private Book[] books; // ... public void setBooks(int i,Book b) { if(b!=null) books[i]=b; } public Book getBooks(int i) {return books[i];} } C# style : public class Bookshop { private Book[] books; // ... public Book this[int i]{ get {return books[i];} set {if(value!=null) books[i]=value;} } } // ... Bookshop standaard=new Bookshop(); standaard[10]=new Book(“Harry Potter”);
  17. 17. 17 Event handling Delegates used to handle events - Java equivalent : inner class object - C/C++ equivalent : function pointer Direct support in C# for events public delegate void TempChangeHandler(double t,ref bool cancel); public class Thermometer { public event TempChangeHandler TempChange; double temp; public double Temperature{ get{return temp;} set{if(temp!=value) { bool cancel=false; TempChange(value,ref cancel); // fire event if(!cancel) temp=value; } } }
  18. 18. 18 Event handling public class TempController { public TempController(Thermometer tm) { tm.TempChange+=new TempChangeHandler(tm_TempChange); } private void tm_TempChange(double t,ref bool cancel) { if(t>100) { cancel=true; System.Console.WriteLine( "Way too hot : WRONG VALUE"); } else { System.Console.WriteLine( "New temperature registered."); } } }
  19. 19. 19 Event handling public class Test { public static void Main() { Thermometer term=new Thermometer(); TempController tc=new TempController(term); term.Temperature=30; Console.WriteLine("Temp = {0}",term.Temperature); term.Temperature=120; Console.WriteLine("Temp = {0}",term.Temperature); } }
  20. 20. 20 Enummerations Standard Java approach public class Period { public final static int DAILY=1; public final static int WEEKLY=2; public final static int MONTHLY=3; public final static int YEARLY=4; } // ... int publicationPeriod=Period.DAILY; // PROBLEM : does not prevent int publicationPeriod=12; ??? C# approach public enum Period{DAILY=1,WEEKLY=2,MONTHLY=3,YEARLY=4}; Period publicationPeriod = Period.WEEKLY;
  21. 21. 21 Enummerations Java 5 approach enum PeriodE{DAILY,WEEKLY,MONTHLY,YEARLY} //... int publicationPeriod=Period.DAILY; System.out.println(publicationPeriod); PeriodE pubPeriod=PeriodE.DAILY; System.out.println(pubPeriod); // OUTPUT : // 1 // DAILY
  22. 22. 22 Iterating over a Collection Standard Java approach for(Iterator i=collection.iterator();i.hasNext();) { Object o=i.next(); // do something with o } for(int i=0;i<array.length;i++) { // do something with array[i] } C# approach foreach(object o in collection) { // do something with o } foreach(int i in array) { // do something with i } Java 5 approach for(Object o : collection) { // do something with o } for(int i : array) { // do something with i }
  23. 23. 23 Extension on “primitive” typesC# struct datatype : - very similar to class (defines attributes and methods) - BUT : - allocated on the stack or in-line (instead of heap) - value type -> pass by value by default - efficient for small types - usage similar to usage of primitive types in Java struct CoupleV { private int x, y; public int X { set { x = value; } get { return x; } } public int Y { set { y = value; } get { return y; } } public string ToString() { return "(" + x + "," + y + ")"; }
  24. 24. 24 Extension on “primitive” types public static void Main() { CoupleV p = new CoupleV(); p.X = 10; p.Y = 20; CoupleV q=new CoupleV(); q.X = 20; q.Y = 30; Console.WriteLine(p.ToString()); Console.WriteLine(q.ToString()); CoupleV[] r = new CoupleV[4]; for (int i = 0; i < r.Length; i++) r[i].X = r[i].Y=i; foreach(CoupleV i in r) Console.WriteLine(i.ToString()); }
  25. 25. 25 Operator Overloading Allows to program type specific operator semantics More restrictive than C++ overloading mechanism - always static - NON virtual (static binding !) ! public static bool operator ==(CoupleV a, CoupleV b) { return ((a.x == b.x) && (a.y == b.y)); } public static Boolean operator !=(CoupleV a, CoupleV b) { return !(a == b); } // ... CoupleV p = new CoupleV();p.X = 10;p.Y = 20; CoupleV q = new CoupleV();q.X = 10;q.Y = 20; Console.WriteLine(p == q); // TRUE Console.WriteLine((object)p == (object)q); // FALSE non-virtual !
  26. 26. 26 Polymorphism Java : all methods virtual (late binding) by default C# (like C++) : methods MUST be declared virtual if late binding applies class A { public virtual void f() {Console.WriteLine("A.f()");} } class B : A { public override void f() {Console.WriteLine("B.f()");} } - shows intention of programmer - more efficient - can prevent later extensions ... - explicit interface implementation (solving name conflicts in case of multiple interface implementation) - possibility to hide base class type/method in derived class
  27. 27. 27 Assemblies Type boundaries - class - namespace (equivalent to Java package) - assembly (equivalent to Java archive) Assemby = exe/dll to deploy - meta-data (files contained, security settings, versioning info, dependencies) - modules (compiled source files) - resources Versioning - contained in assemby info - allows to run multiple versions of same types on same CLR
  28. 28. 28 Visibility private same as Java = default for interface and enum members public same as Java =default for struct and class members protected visible in type itself or derived types internal visible in assembly = default for non-nested types internal protected visible from type itself, in same assembly and in derived types (= private or protected or internal) Type can not be more accessible then types used for its declaration
  29. 29. 29 Parameter modifiers Passing references ref pass reference to method requires parameter is assigned definite value before method entry out requires definite parameter assignment before returning from method call Variable number of arguments params can be applied to last argument of method Parameter modifiers are part of method signature
  30. 30. 30 Parameter modifiers static void swap(ref int a, ref int b) { int t = a; a = b; b = t; } static void OneMore(int i, out int j) { j = i + 1; } static int sum(params int[] x) { int r = 0; foreach (int i in x) r += i; return r; } // ... int x = 1, y = 2; swap(ref x, ref y); Console.WriteLine("{0} - {1}",x, y); // 2 - 1 OneMore(x, out y); Console.WriteLine("{0} - {1}", x, y); // 2 - 3 Console.WriteLine(sum(1, 2, 3)); // 6 Console.WriteLine(sum(3, 4, 5, 6)); // 18
  31. 31. 31 Attributes Allow to extend language built-in declarative constructs - Pre-defined attributes (e.g. Serialized) - Custom attributes Can be applied to - class - method - field - parameter Attributes and values can be retrieved at runtime
  32. 32. 32 Field modifiers const - value calculated at compile time - equivalent to Java final readonly - value calculated at runtime - can only be assigned once ! - allows to retrieve setting (“a not so constant constant ...”)
  33. 33. 33 Pointer arithmetic allowed in sections marked as unsafe pointer type : <type>* dereferencing : *<pointer expression> address calculation : &<variable> Garbage collector should NOT move around objects used in unsafe regions MUST be declared fixed
  34. 34. 34 Pointer arithmetic unsafe static void AdditionOne(int[] b) { int l=b.Length; fixed (int* a = b) { int* p = a; for (int i = 0; i < l; i++,p++) *p = (*p) + 1; } } //... int[] k ={ 1, 2, 3, 4 }; foreach (int a in k) Console.WriteLine("{0}", a); // 1 2 3 4 AdditionOne(k); foreach (int a in k) Console.WriteLine("{0}", a); // 2 3 4 5
  35. 35. 35 Rectangular Arrays int[,,] a=new int[3,4,5]; // rectangular array // single reference variable a[1,2,3]=20; int[][][] b=new int[3][4][5]; // jagged array b[1][2][3]=30; ...
  36. 36. 36 Constructors - Destructors Very similar to Java constructors – finalizers Constructor : can contain explicit constructor call specified outside constructor body - call to other constructor of same type : this(...) - call to base class constructor : base(...) Destructor NOT for value type NO explicit calls to destructor C++-like syntax (actually expands to calling Finalize) class A { public A():this(1){} public A(int i):base(i){} ~A() {/* Destructor */} }
  37. 37. 37 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types
  38. 38. 38 C# type system Value types (struct, enum) Reference types (class, array, delegate, interface) Pointer type struct CoupleV { private int x, y; public CoupleV(int xx, int yy) { x = xx; y = yy; } public int X { set { x = value; } get { return x; } } public int Y { set { y = value; } get { return y; } } public override string ToString() { return "(" + x + "," + y + ")"; } }
  39. 39. 39 C# type system class CoupleR { private int x=0, y=0; public CoupleR(int xx, int yy) { x = xx; y = yy; } public int X { set { x = value; } get { return x; } } public int Y { set { y = value; } get { return y; } } public override string ToString() { return "(" + x + "," + y + ")"; } }
  40. 40. 40 C# type system // ... CoupleR a = new CoupleR(1, 2); CoupleR b = a; CoupleV c = new CoupleV(3, 4); CoupleV d = c; a.X = 7; c.X = 7; Console.WriteLine(a); // (7,2) Console.WriteLine(b); // (7,2) Console.WriteLine(c); // (7,4) Console.WriteLine(d); // (3,4)
  41. 41. 41 Type unification all struct and class types derive from object (pointer types do not ...) “simple” (“primitive”) types are actually structs int : alias for System.Int32 long : alias for System.Int64 ... boxing – unboxing - value type -> reference type : copy made (automatic) - reference type -> value type : explicit cast necessary int x=12; object o=x; // box int y=(int)o; // unbox through downcast
  42. 42. 42 Available types Value types signed integer : sbyte, short, int, long unsigned integer : byte, ushort, uint, ulong floating point : float, decimal, double logical : bool characters : char Reference types object string standard notations for constants apply (U : unsigned, L : long) standard rules for conversions apply
  43. 43. 43 Checked Arithmetic checked(<expression>) checked {/* block */} checks for integral overflows generates runtime exception OverflowException unchecked(<expression>) unchecked{/* block */} turns off compile time bounds checking
  44. 44. 44 Control flow statements Same as in Java, BUT switch : no “fall through” behaviour each case must end with jump (break, goto, ...) foreach goto label; // ... int x=0; loop : x++; if(x<5) goto loop;
  45. 45. 45 Namespaces Similar to java packages w.r.t. avoiding name clashes BUT : no boundary for accessibility Can be nested namespace A { namespace B { class CL { } } } // ... A.B.CL x=new A.B.CL(); Alternative using A.B; CL x=new CL(); Global namespace = default surrounding namespace
  46. 46. 46 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types
  47. 47. 47 Classes [<attributes>][unsafe][<access modifier>][new] [abstract | sealed] <class name> [: <base class> | : <interfaces> | : <base class>,<interfaces> ] { <class members> } Class members • Fields • Constants • Properties • Indexers • Methods • Events • Nested type (like Java static inner class, no outer object)
  48. 48. 48 Modifiers Accessibility (visibility) : private, internal, protected, public Inheritable sealed : can not be overridden/inherited (Java equivalent : final) - sealed class - sealed method abstract : MUST be overridden/inherited - abstract class - abstract method class/method can not be sealed AND abstract Parameter modifiers : ref,out,params Class member/instance member : static Late binding/static binding : virtual, override, new Dangerous ? : unsafe - unsafe class - unsafe method - unsafe property
  49. 49. 49 Inheritance class A {} class B : A {} class C : B {} class D : A {} Runtime type checking (RTTI) operator is if(a is A) {/* ... */} if(b is A) {/* ... */} // true if b is A or B Conversions : - widening conversions (upcast) : automatic B b = new B(); C c = new C(); D d = new D(); A ab = b; A ac = c; B bc = c; B bd = d; // compile time error A ad = d; - narrowing (cntd.)
  50. 50. 50 Inheritance - narrowing conversions : cast necessary - simple downcast : B ba=(B)ab; // OK C ca=(C)ac; // OK D da=(D)ad; //OK D dc=(D)ac; // runtime error - safe downcast (evaluates to null if unsuccesful) B ba = ab as B; C ca = ac as C; D dc = ac as D; // null
  51. 51. 51 Polymorphism Key idea : late binding, based on dynamic object type C# : use virtual methods, override in derived class class A { public virtual void f() {Console.WriteLine("A.f()");} } class B : A { public override void f() {Console.WriteLine("B.f()");} } class C : B { public override void f() { Console.WriteLine("C.f()"); } } class D : A { public override void f() {Console.WriteLine("D.f()");} }
  52. 52. 52 Polymorphism A a = new A(); B b = new B(); C c = new C(); D d = new D(); a.f(); // A.f() b.f(); // B.f() c.f(); // C.f() d.f(); // D.f() A[] a = new A[] { new A(), new B(), new C(), new D() }; foreach(A aa in a) aa.f(); // A.f() // B.f() // C.f() // D.f()
  53. 53. 53 Polymorphism Sealing class A { public virtual void f() {Console.WriteLine("A.f()");} } class B : A { public sealed override void f() {Console.WriteLine("B.f()");} } class C : B { public override void f() { Console.WriteLine("C.f()"); } } NOT allowed
  54. 54. 54 Polymorphism Hiding base class member : new class A {public virtual void f() {Console.WriteLine("A.f()");}} class B : A {public override void f() {Console.WriteLine("B.f()");}} class C : B {public new void f() { Console.WriteLine("C.f()"); }} class D : A {public override void f() {Console.WriteLine("D.f()");}} A aa = new A(); aa.f(); // A.f() B bb = new B(); bb.f(); // B.f() C cc = new C(); cc.f(); // C.f() D dd = new D(); dd.f(); // D.f() A ab = new B(); ab.f(); // B.f() A ac = new C(); ac.f(); // B.f() A ad = new D(); ad.f(); // D.f(); B bc = new C(); bc.f(); // B.f(); A[] a = new A[] { new A(), new B(), new C(), new D() }; foreach(A o in a) o.f(); // A.f() B.f() B.f() D.f()
  55. 55. 55 Polymorphism Hiding base class member : new class A {public virtual void f() {Console.WriteLine("A.f()");}} class B : A {public override void f() {Console.WriteLine("B.f()");}} class C : B {public new void f() { Console.WriteLine("C.f()"); }} class D : A {public new void f() {Console.WriteLine("D.f()");}} A aa = new A(); aa.f(); // A.f() B bb = new B(); bb.f(); // B.f() C cc = new C(); cc.f(); // C.f() D dd = new D(); dd.f(); // D.f() A ab = new B(); ab.f(); // B.f() A ac = new C(); ac.f(); // B.f() A ad = new D(); ad.f(); // A.f(); B bc = new C(); bc.f(); // B.f(); A[] a = new A[] { new A(), new B(), new C(), new D() }; foreach(A o in a) o.f(); // A.f() B.f() B.f() A.f()
  56. 56. 56 Polymorphism new - define method as new (even if method with same signature, possibly sealed, exists in base class) - define new property - define new field class A {protected double i; public double I {set{i = value;} get{return i;} } public sealed void f() {Console.WriteLine("A.f()");} } class B : A {private new int i; public new int I {set{i = value;} get{return i;} } public new void f() {Console.WriteLine(“B.f()");} }
  57. 57. 57 Structs Struct = class except for • value type, allocated on the stack • is implicitely sealed (inherit from single type, System.ValueType), can implement several interfaces • can NOT have destructor • NO field initializers (initialization to 0) • NO constructor that leaves fields uninitialized struct CoupleV : A // not allowed unless A is interface { private int x=1, y=1; // NOT allowed : field initializer public CoupleV(int xx) { x = xx; } // NOT allowed : partial initialization public CoupleV(int xx, int yy) { x = xx; y = yy; } // allowed }
  58. 58. 58 Interfaces Interface = class except for • no implementation, (pure abstract class) • can be supertype of struct (class can not !) Interface members : - methods - properties - indexers - events always : implicitly public, abstract, virtual and non static
  59. 59. 59 Interfaces interface IP{void f();} interface IQ{void g();} class A : IP{ public virtual void f() {Console.WriteLine("A.f()");} } class B : A,IQ { public override void f() {Console.WriteLine("B.f()");} public virtual void g() {Console.WriteLine("B.g()");} } class C : B { public override void f() { Console.WriteLine("C.f()"); } public override void g() { Console.WriteLine("C.g()"); } } class D : A{ public override void f(){Console.WriteLine("D.f()");} } class E : D,IQ { public override void f() { Console.WriteLine("E.f()"); } public virtual void g() { Console.WriteLine("E.g()"); } }
  60. 60. 60 Interfaces IP[] p = new IP[] { new A(), new B(), new C(), new D(), new E() }; IQ[] q = new IQ[] { new B(), new C(), new E() }; foreach (IP pp in p) pp.f(); foreach (IQ qq in q) qq.g(); // A.f() // B.f() // C.f() // D.f() // E.f() // B.g() // C.g() // E.g() Extending an interface interface IPP : IP { void ff(); }
  61. 61. 61 Explicit interface implementation PROBLEM : implement two interfaces with name collision -> explicit (instead of implicit) interface implementation interface U { void a(); } interface V { void a(); } class O : U, V { void U.a() { Console.WriteLine("A.ua()"); } void V.a() { Console.WriteLine("A.va()"); } } // ... O o = new O(); // o.a(); // NOT allowed ((U)o).a(); // A.ua() ((V)o).a(); // A.va()
  62. 62. 62 Explicit interface implementation LIMITATIONS (compared to implicit implementations) • NO late binding no polymorphism related modifiers (no abstract, virtual, override, new) • NO access modifier usage requires cast to interface access modifier mentioned there is used implicitely Same rules (as with classes) to • convert between types • to convert to structs
  63. 63. 63 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. Operator Overloading 6. Event driven programming 7. .NET Framework Class Library 8. A GUI in C# 9. A web service in C#
  64. 64. 64 Operator overloading Idea • treat operators (+,-,*,/,%,...) as special functions (keyword operator) • give special meaning to operator according to class semantics • allows elegant programming for math-oriented software • important issue : what happens in case of mixed type expressions ? -> need to overload also type conversion -> quite complex to keep consistent -> not available in Java (but proposals are on the way ...)
  65. 65. 65 C# Operator overloading Operators to overload + - ! ~ ++ -- (unary) (binary) + - * / % arithmetic & | ^ bit logic << >> bit shift == != > < >= <= relational CAN NOT BE OVERLOADED : - address related operators (unary *, &) - assignment ! (cf. C++ ...) ONLY static operators allowed LOGIC pairs (MUST be overloaded together) == and != < and > <= and >=
  66. 66. 66 Indirect overloading To keep things consistent (developer might forget to overload ...) - && and || are evaluated using & and | - [] operator overloaded through indexers - combined assignment operators (+=, -=, *=, /=, ...) evaluated using non-combined counterparts
  67. 67. 67 Value equality Operators == and != default to reference equality If other behavior is needed : - override Equals method (cf. Java) - redirect Equals to “==“ and “!=“ -> allows compatibility with .NET languages NOT supporting operator overloading -> allows polymorphism
  68. 68. 68 Value equality class Point { protected int x, y; public Point(int xx, int yy) { x = xx; y = yy; } public Point(int xx) : this(xx, xx) { } public Point() : this(0) { } public override string ToString() { return "<"+x+","+y+">"; } public static bool operator ==(Point a, Point b) { return (a.x == b.x) && (a.y == b.y); } public static bool operator !=(Point a, Point b) { return !(a == b); } }
  69. 69. 69 Value equalityProblem Collections framework heavily uses Equals()-method (implementation of no-duplicate collections such as Sets) -> whenever == and != overloaded -> Equals() should be overridden public override bool Equals(object o) { if (o is Point) { Point p = (Point)o; return this == p; } else return false; } DO NOT call Equals() from within == and != ...
  70. 70. 70 Value equality : inheritance class Point3D : Point { protected int z; public Point3D(int xx,int yy,int zz):base(xx,yy){z=zz;} public override string ToString() { return "<"+x+","+y+","+z+">"; } } // ... Point a=new Point(1,1); Point b=new Point(2,2); Point c = new Point(2, 2); Point3D d=new Point3D(3,3,3); Point3D e = new Point3D(3, 3, 3); Point3D f = new Point3D(3, 3, 4); Console.WriteLine(a); // <1,1> Console.WriteLine(b); // <2,2> Console.WriteLine(e); // <3,3,3> Console.WriteLine(f); // <3,3,4>
  71. 71. 71 Value equality : inheritance Console.WriteLine(a == b); // False Console.WriteLine(a == c); // False Console.WriteLine(a == d); // False Console.WriteLine(b == c); // True -> value ! Console.WriteLine(b == d); // False Console.WriteLine(c == d); // False Console.WriteLine(d == e); // True Console.WriteLine(e == f); // True Operators == and != should be overloaded in Point3D public static bool operator ==(Point3D a, Point3D b) { return (a.x == b.x) && (a.y == b.y)&&(a.z==b.z); } public static bool operator !=(Point3D a, Point3D b) { return !(a == b); } // ... Console.WriteLine(e == f); // False
  72. 72. 72 Value equality : polymorphismPoint[] p ={ new Point(1, 1), new Point(2, 2), new Point3D(1, 1, 1), new Point3D(2, 2, 2) }; Point s1 = new Point(2, 2) Point s2 = new Point3D(2, 2, 2); foreach (Point pp in p) Console.WriteLine(pp == s1); foreach (Point pp in p) Console.WriteLine(pp == s2); // False True False True // False True False True CHANGE operator in base class (!) public static bool operator ==(Point a, Point b) { if(((a is Point3D)&&!(b is Point3D))|| (!(a is Point3D)&&(b is Point3D))) return false; else return (a.x == b.x) && (a.y == b.y); } public static bool operator !=(Point a, Point b) { return !(a == b); } // False True False False // False False False True
  73. 73. 73 Overloading arithmetic operators Operator + Point p: translate over p Operator + int i: translate over Point(i,i) public static Point operator +(Point a, Point b){ return new Point(a.x + b.x,a.y + b.y); } public static Point operator +(Point a,int i){ return new Point(a.x + i, a.y + i); } public static Point operator +(int i, Point a){ return a + i; } //... Point a = new Point(10, 20); Point b = new Point(20, 30); Console.WriteLine(a + b); //<30,50> Console.WriteLine(a + 100); //<110,120> Console.WriteLine(100 + a + b); //<130,150>
  74. 74. 74 Type Conversion Two versions implicit not dangerous, can be invoked by compiler whenever needed explicit dangerous, only done if explicitely asked e.g. conversion to and from int Point-to-int : max value of x and y (looses info !) int-to-Point : Point on diagonal (no info lost !)
  75. 75. 75 Type Conversion public static Point operator +(Point a,int i) { Console.WriteLine("+(P,i)"); return new Point(a.x + i, a.y + i); } public static Point operator +(int i, Point a) { Console.WriteLine("+(i,P)"); return a + i; } public static implicit operator Point(int i) { Console.WriteLine("(P)i"); return new Point(i, i); } public static explicit operator int(Point p) { Console.WriteLine("(i)P"); return (p.x > p.y) ? p.x : p.y; }
  76. 76. 76 Type Conversion Point a = new Point(10,20); Console.WriteLine((Point)5); // (P)i <5,5> Console.WriteLine(a + 5); // +(P,i) <15,25> Console.WriteLine((int)a + 5); //(i)P 25 In case NO +(Point,int) and +(int,Point) operators : Console.WriteLine((Point)5); // (P)i <5,5> Console.WriteLine(a + 5); // (P)i <15,25> Console.WriteLine((int)a + 5); // (i)P 25
  77. 77. 77 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. Operator Overloading 6. Event driven programming • delegates • events 7. .NET Framework Class Library 8. A GUI in C# 9. A web service in C
  78. 78. 78 Delegates[<attributes>][unsafe][<access modifiers>] [new]delegate <return type> <delegate name> (<parameter list>); = type defining method signature - instance can hold (list of) method(s) with matching signature public delegate bool Filter(string s); class Del{ public static void Main(){ String[] r = new String[] { "a fair Lady", "the king and I", "hye buzz", "a beautiful mind", "the zzz" }; Filter f=new Filter(StartWithA); ArrayList a=Show(r,f); Console.WriteLine("Starting with a :"); foreach (String s in a) Console.WriteLine(s); f=new Filter(EndWithZ); ArrayList z = Show(r, f); Console.WriteLine("Ending with z :"); foreach (String s in z) Console.WriteLine(s); } //... }
  79. 79. 79 Delegatesclass Del { // ... public static bool StartWithA(String s) { return s[0] == 'a'; } public static bool EndWithZ(String s) { return s[s.Length-1] == 'z'; } public static ArrayList Show(String[] s, Filter f) { ArrayList l = new ArrayList(); foreach(String i in s) if(f(i)) l.Add(i); return l; } } Starting with a : a fair Lady a beautiful mind Ending with z : hye buzz the zzz
  80. 80. 80 Multicast Delegates Use operators += and -= to add/remove delegates to other delegate if non-void : return value of last invocation is returned public delegate void M(int i); class Multi { // ... public static void Print(int i) { Console.WriteLine("i = {0}",i); } public static void Sqrt(int i) { Console.WriteLine(Math.Sqrt(i)); } public static void EndMessage(int i) { Console.WriteLine("Ending ..."); } }
  81. 81. 81 Multicast Delegates// public delegate void M(int i); class Multi { // ... public static void Main() { M m = null; Console.WriteLine("----------------------------"); m += new M(Print); m += new M(Sqrt); m += new M(EndMessage); m(12); Console.WriteLine("----------------------------"); m += new M(Print); m(16); Console.WriteLine("----------------------------"); m -= new M(Sqrt); m(25); Console.WriteLine("----------------------------"); m -= new M(Print); m(36); Console.WriteLine("----------------------------"); } } ----------------- i = 12 3,46410161513775 Ending ... ----------------- i = 16 4 Ending ... i = 16 ----------------- i = 25 Ending ... i = 25 ----------------- i = 36 Ending ... -----------------
  82. 82. 82 Multicast Delegates From within object -> invoked on this-object public delegate void F(); public class A { public F f; private int i = 0; public A(int i) { this.i = i; f=null; f+=new F(Print); f+=new F(Inc); f+=new F(Print); f+=new F(Dec); f+=new F(Dec); f+=new F(Print); } public void Inc() { i++; } public void Dec() { i--; } public void Print() {Console.WriteLine(this);} public override string ToString(){return "<"+i+">";} public void IncAndDec() {f();}
  83. 83. 83 Multicast Delegates From within object -> invoked on this-object // ... public static void Test() { A a=new A(10); a.IncAndDec(); a.f(); } } class MultiObj { public static void Main() { A.Test(); A a = new A(20); a.f(); } } <10> <11> <9> <9> <10> <8> <20> <21> <19>
  84. 84. 84 Delegate versus ... Delegate vs. C function pointer - type safe (unless in unsafe regions ...) - can hold multiple methods to invoke - can hold instance to invoke method upon Delegate vs. Interface - multiple methods to invoke (could be implemented through list of interface objects) - any problem solved with delegates can be solved using interface types - “more elegant”
  85. 85. 85 Delegate versus Inteface interface IF { bool Filter(string s); } class StartWithAFilter : IF { public bool Filter(string s) { return s[0] == 'a'; } } class EndWithZFilter : IF { public bool Filter(string s) { return s[s.Length - 1] == 'z'; } }
  86. 86. 86 Delegate versus Inteface class Test { public static void Main() { String[] r = new String[] { "a very fair Lady", "the king and a z", "hye buzzy", "a beautiful mind for z", "the zzz" }; ArrayList a = Show(r, new StartWithAFilter()); Console.WriteLine("Starting with a :"); foreach (String s in a) Console.WriteLine(s); ArrayList z = Show(r, new EndWithZFilter()); Console.WriteLine("Ending with z :"); foreach (String s in z) Console.WriteLine(s); } public static ArrayList Show(String[] s, IF f) { ArrayList l = new ArrayList(); foreach (String i in s) if (f.Filter(i)) l.Add(i); return l; } } Starting with a : a very fair Lady a beautiful mind for z Ending with z : the king and a z a beautiful mind for z the zzz
  87. 87. 87 Events A B events - notification from A -> B - WITHOUT calling directly method on B use of intermediary - event listeners + event handlers - in C# : implemented through delegates event
  88. 88. 88 Events A B event Event Source Event Sink - delegate defined to fix handler signature - source class declares ability to fire event -> public (downcast) multicast delegate d - delegates registered with d to get notified - source class fires event by calling delegate d d Delegate delegate delegate delegate
  89. 89. 89 Events : Example Customer arrives in business centre -> generates event -> interested parties are notified Delegate conventions for eventing - first argument : identifies source of event - second argument : additional info subclass of EventArgs Example - ID = object reference - additional info : - time of event - urgency
  90. 90. 90 Events : Example Delegate signature delegate void CustomerHandler(object s, CustomerArgs e) public delegate void CustomerHandler(object o,CustomerArgs e); enum Priority {LOW=0,NORMAL=1,HIGH=2}; class CustomerArgs : EventArgs { private DateTime d; public Priority p; public static Random r = new Random(); public DateTime Time { get { return d; } } public Priority Urgency { get {return p;} } public CustomerArgs() { d = DateTime.Now; p=(Priority)(r.Next(3)); } } Preliminaries • Delegate declaration • Definition of event handler argument type
  91. 91. 91 Events : Example public class Customer { private string name; public event CustomerHandler CustomerArrival; public string Name { get { return name; } } public Customer(string n){name = n;} public void arrive() { if (CustomerArrival != null) { CustomerArgs args = new CustomerArgs(); CustomerArrival(this, args); // fire the event; } } public override string ToString(){return "<Customer : "+name+">";} } Event source class : Customer • Declares event • Listeners will register to event • FIRES event when needed
  92. 92. 92 Events : Example class HotelService {private string n; public HotelService(string n) {this.n=n;} public string Name{get{return n;}} public void CustomerArrivalNotification(object o,CustomerArgs a) { Console.WriteLine(this + " : guest " + (Customer)o + " arrived at " + (a.Time)+"(Priority : "+a.Urgency+")"); } public override string ToString() { return "Hotel service : "+n; } } class HotelPersonnel {private string n; public HotelPersonnel(string n) {this.n=n;} public string Name{get{return n;}} public void CustomerArrivalNotification(object o,CustomerArgs a) { Console.WriteLine(this + " : guest " + (Customer)o + " arrived at" + (a.Time) + "(Priority : " + a.Urgency + ")"); } public override string ToString() { return "Hotel personnel : "+n; } } Event sink classes : • HotelService • HotelPersonnel • declare a method conforming to delegate signature
  93. 93. 93 Events : Example class CustomerApp { public static void Main() { Customer[] c=new Customer[] {new Customer("Bart De Poorter"), new Customer("George Bush"), new Customer("Condaleeza Rice"), new Customer("Mahatma Ghandi")}; HotelService[] hs = new HotelService[] { new HotelService("House keeping"), new HotelService("Accounting"), new HotelService("Reception") }; HotelPersonnel[] hp = new HotelPersonnel[] { new HotelPersonnel("Manager"), new HotelPersonnel("Mr. BigBoss (owner)") }; foreach(HotelService h in hs) { foreach(Customer cu in c) cu.CustomerArrival+= new CustomerHandler(h.CustomerArrivalNotification); } // ... Main method • instantiates simulation objects • binds sinks to sources
  94. 94. 94 Events : Example // ... foreach (HotelPersonnel h in hp) { c[1].CustomerArrival += new CustomerHandler(h.CustomerArrivalNotification); c[2].CustomerArrival += new CustomerHandler(h.CustomerArrivalNotification); } Console.WriteLine("Starting simulation ----------------"); foreach (Customer cc in c) { cc.arrive(); try { System.Threading.Thread.Sleep(1000); } catch (System.Threading.ThreadInterruptedException e) { } Console.WriteLine("---------------------"); } } }
  95. 95. 95 Events : Example Starting simulation ---------------- Hotel service : House keeping : guest <Customer : Bart De Poorter> arrived at 14/12/2005 9:57:06(Priority : NORMAL) Hotel service : Accounting : guest <Customer : Bart De Poorter> arrived at 14/12/2005 9:57:06(Priority : NORMAL) Hotel service : Reception : guest <Customer : Bart De Poorter> arrived at 14/12/2005 9:57:06(Priority : NORMAL) --------------------- Hotel service : House keeping : guest <Customer : George Bush> arrived at 14/12/2005 9:57:07(Priority : LOW) Hotel service : Accounting : guest <Customer : George Bush> arrived at 14/12/2005 9:57:07(Priority : LOW) Hotel service : Reception : guest <Customer : George Bush> arrived at 14/12/2005 9:57:07(Priority : LOW) Hotel personnel : Manager : guest <Customer : George Bush> arrived at14/12/2005 9:57:07(Priority : LOW) Hotel personnel : Mr. BigBoss (owner) : guest <Customer : George Bush> arrived at 14/12/2005 9:57:07(Priority : LOW) --------------------- Hotel service : House keeping : guest <Customer : Condaleeza Rice> arrived at 14/12/2005 9:57:08(Priority : NORMAL) Hotel service : Accounting : guest <Customer : Condaleeza Rice> arrived at 14/12/2005 9:57:08(Priority : NORMAL) Hotel service : Reception : guest <Customer : Condaleeza Rice> arrived at 14/12/2005 9:57:08(Priority : NORMAL) Hotel personnel : Manager : guest <Customer : Condaleeza Rice> arrived at14/12/2005 9:57:08(Priority : NORMAL) Hotel personnel : Mr. BigBoss (owner) : guest <Customer : Condaleeza Rice> arrived at14/12/2005 9:57:08(Priority : NORMAL) --------------------- Hotel service : House keeping : guest <Customer : Mahatma Ghandi> arrived at 14/12/2005 9:57:09(Priority : HIGH) Hotel service : Accounting : guest <Customer : Mahatma Ghandi> arrived at 14/12/2005 9:57:09(Priority : HIGH) Hotel service : Reception : guest <Customer : Mahatma Ghandi> arrived at 14/12/2005 9:57:09(Priority : HIGH) ---------------------
  96. 96. 96 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. Operator Overloading 6. Event driven programming 7. .NET Framework Class Library 8. A GUI in C# 9. A web service in C#
  97. 97. 97 FCL -CLS compliant set of managed type - accessible from all .NET languages - grouping (3542 types) : - logically in namespaces (120) - deployed as a set of assemblies (36) of .NET framework System - collection of core classes (Object, ValueType, Enum, Convert, Exception) - core interfaces (ICloneable, IComparable, ...) - time related classes (DateTime, TimeSpan) - support for - delegates - mathematical operations - custom attributes (Attribute) - exception handling - strings (String)
  98. 98. 98 FCL System.Text - immutable string (System.String) - mutable string (StringBuilder) - regular expressions (System.Text.RegularExpressions) C# string is alias for System.String overloaded “==“ operator for equality check (NOT in Java !) indexing strings : use normal indexing mechanism ([]) string a=“abcde”; char c=a[2]; formatting strings (Format()-method) format specifier string : {ParamIndex[,MinWidth][:FormatString]} e.g. “Value of account {0} is {1:C}” (C -> “Currency”)
  99. 99. 99 FCL System.Collections - Java-like set of interfaces and classes, implementing popular data structures (ArrayList, Queue, Stack, BitArray, ...) - System.Array is base type for all array types - generics as of .NET v 2.0 (System.Collections.Generics) to iterate over Collection : - Collection implements IEnumerable public interface IEnumerable { IEnumerator GetEnumerator(); } - iterator implements IEnumerator public interface IEnumerator { bool MoveNext(); object Current {get;} void Reset(); } - also : foreach idiom can be used
  100. 100. 100 FCL iterator for Dictionary (Java Map) public interface IDectionaryEnumerator : IEnumerator { DictionaryEntry Entry {get;} object Key {get;} object Value {get;} } IEnumerable ICollection IList IDictionary get iterator support for counting converting to array indexed collection
  101. 101. 101 FCLclass Array : ICollection, IEnumerable, IList fixed size indexed array class ArrayList : IList dynamically sized array class Hashtable : IDictionary standard dictionary key/value pairs hash computed using GetHashCode() method -> should be overridden class Queue FIFO data structure methods to queue and dequeue class Stack LIFO data structure key methods : push and pop
  102. 102. 102 FCL class Bitarray compressed form of bool[] (one bit per boolean) class SortedList : IDictionary sorted to increase lookup efficiency (binary search instead of linear search) class StringCollection : ICollection special purpose collection for storing strings class StringDictionary : IEnumerable idem for storing string maps
  103. 103. 103 FCL : Examplespublic static void Print(ICollection c) { int j = 0; foreach(object i in c) Console.WriteLine("{0} -> {1}",j++,i); Console.WriteLine("--------------------"); } ArrayList al = new ArrayList(); al.Add("Wim"); al.Add("Ann"); al.Add("Bram"); al.Add("Bart"); al.Add("Greet"); Print(al); al.Sort(); Print(al); Console.WriteLine(al[1]); al[1] = "BART"; Print(al); 0 -> Wim 1 -> Ann 2 -> Bram 3 -> Bart 4 -> Greet -------------------- 0 -> Ann 1 -> Bart 2 -> Bram 3 -> Greet 4 -> Wim -------------------- Bart 0 -> Ann 1 -> BART 2 -> Bram 3 -> Greet 4 -> Wim --------------------
  104. 104. 104 FCL : ExamplesHashtable h = new Hashtable(); h["Wim"] = "onetwothree"; h["Bram"] = "123"; h["Greet"] = "Da Vinci"; h["Ann"] = "My fair lady"; Console.WriteLine(h["Bram"]); // 123 Queue q = new Queue(); Stack s = new Stack(); int[] a ={ 1, 2, 3, 4 }; foreach (int i in a) {q.Enqueue(i); s.Push(i);} Print(q); Print(s); Console.WriteLine(q.Dequeue()); Console.WriteLine(s.Pop()); Print(q); Print(s); 123 0 -> 1 1 -> 2 2 -> 3 3 -> 4 -------------------- 0 -> 4 1 -> 3 2 -> 2 3 -> 1 -------------------- 1 4 0 -> 2 1 -> 3 2 -> 4 -------------------- 0 -> 3 1 -> 2 2 -> 1 --------------------
  105. 105. 105 FCL : SortingTwo options : - object ordering implemented in the class itself public interface IComparable { int CompareTo(object o); } - delegate ordering to special object public interface IComparer { int Compare(object o1,object o2); } comparing must follow special contract 1. if a comes before b -> a.CompareTo(b)<0 2. if a is equal to b -> a.CompareTo(b) == 0 3. if a comes after b -> a.CompareTo(b)>0 4. null first -> a.CompareTo(null)>0 5. a.CompareTo(b) -> a.GetType() == b.GetType()
  106. 106. 106 FCL System.IO - standard in, out and error stream - binary and text file I/O - registering/notification of filesystem events - access of user specific secure storage (“Isolated Storage”) - System.Console - System.IO.IsolatedStorage System.Net - classes for network communication - raw socket access, TCP, UDP sockets - HTTP support - System.Net - System.Net.Sockets - System.IO.Stream
  107. 107. 107 FCL System.Security - security policies, principals, permission sets, evidence (authentication, key, ...) - cryptographic library System.Threading - support for thread management and pool management - synchronization mechanisms - locks (monitor): serialized access - pulse/wait : notify waiting threads - System.Timers - System.Thread
  108. 108. 108 FCL System.Reflection - retrieve type information (methods, class names, signatures, ...) at runtime - retrieve (custom) attributes at runtime -> for each custom attribute : - CLR creates object - retrieved using reflection interface - retrieve metadata at runtime - assembly info (version, target OS, ...) - data to create custom attributes stored as metadata
  109. 109. 109 FCL System.Runtime.Serialization - write object graph to/from stream (file or network) - default serializers : XML and binary - serializability : use non-custom attribute [Serializable] - System.SerializableAttribute - System.NonSerializableAttribute System.Runtime.Remoting - distributed object model of .NET - calls can be : synchronous, asynchronous, one-way - transport protocol : TCP, HTTP or SMTP - format : binary or SOAP - naming service, activation service, marshalling, messaging
  110. 110. 110 FCL System.Web.Services - in fact part of ASP.NET (not part of CLR) - describe, discover and publish web services System.Data - known as ADO.NET - classes to support database access System.Xml - schemas, namespaces, parsing (DOM,SAX) - implementation of XSLT, XPath, SOAP1.1
  111. 111. 111 FCL System.Drawing - support for graphics - known as GDI+ - brushes, fonts, bitmaps, rendering, drawing primitives, ... System.Windows.Forms - Rich client applications (“classic GUIs”) - known as “Windows Forms” - forms package, GUI components and RAD component model System.Web - Thin client applications - known as “Web Forms” - server side package creates HTML UI - support for session management (state), security, deployment, ... - part of ASP.NET
  112. 112. 112 FCL System.Globalization - date/time conversions - string adaptation to locale - resource file to centralize locale data System.Configuration - per user, per application configuration management System.EnterpriseServices - advanced services - distributed transaction, object pooling, queuing, event handling - reliable asynchronous messaging - access to directory service
  113. 113. 113 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. Operator Overloading 6. Event driven programming 7. .NET Framework Class Library 8. A GUI in C# 9. A web service in C#
  114. 114. 114 GUIs in .NET - heavily uses delegates - event subscription - event notification - Visual Studio .NET contains IDE to assist GUI development - choose New Project -> “Windows Application” (instead of “Console Application”) - Add WinForms as needed - Drop components from ToolBox on each form - Change component state in IDE generated code - Code event handlers
  115. 115. 115 Example : incrementor System.Windows.Forms.Button declares properties : Name, Text fires events : System.EventHandler Click System.Windows.Forms.TextBox declares properties : Name, Text System.Windows.Forms.Form declares properties : Name, Text Controls (container) fires events : System.EventHandler Load
  116. 116. 116 Example : incrementor Main()-method using System; using System.Collections.Generic; using System.Windows.Forms; namespace WindowsApplication1 { static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } } } IDE-generated [Program.cs]
  117. 117. 117 Example : incrementor Form1-class namespace WindowsApplication1 { partial class Form1 { /// <summary> /// Required designer variable. /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// Clean up any resources being used. /// </summary> /// <param name="disposing">true if managed resources /// should be disposed; otherwise, false.</param> protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } IDE-generated (edited) [Form1.Designer.cs]
  118. 118. 118 Example : incrementor #region Windows Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { this.button1 = new System.Windows.Forms.Button(); this.textBox1 = new System.Windows.Forms.TextBox(); this.SuspendLayout(); // // button1 // this.button1.Location = new System.Drawing.Point(92, 150); this.button1.Name = "button1"; this.button1.Size = new System.Drawing.Size(75, 23); this.button1.TabIndex = 0; this.button1.Text = "Click here"; this.button1.UseVisualStyleBackColor = true; this.button1.Click += new System.EventHandler(this.button1_Click); IDE-generated (edited) [Form1.Designer.cs] Form1-class
  119. 119. 119 Example : incrementor Form1-class // // textBox1 // this.textBox1.Location = new System.Drawing.Point(78, 103); this.textBox1.Name = "textBox1"; this.textBox1.Size = new System.Drawing.Size(100, 20); this.textBox1.TabIndex = 1; this.textBox1.TextChanged += new System.EventHandler(this.textBox1_TextChanged); IDE-generated (edited) [Form1.Designer.cs]
  120. 120. 120 Example : incrementor // // Form1 // this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; this.ClientSize = new System.Drawing.Size(292, 266); this.Controls.Add(this.textBox1); this.Controls.Add(this.button1); this.Name = "Form1"; this.Text = "Incrementer"; this.Load += new System.EventHandler(this.Form1_Load); this.ResumeLayout(false); this.PerformLayout(); } #endregion private System.Windows.Forms.Button button1; private System.Windows.Forms.TextBox textBox1; } } IDE-generated (edited) [Form1.Designer.cs] Form1-class
  121. 121. 121 Example : incrementor namespace WindowsApplication1 { public partial class Form1 : Form { int i = 0; public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e){} private void button1_Click(object sender, EventArgs e) { i++; textBox1.Text = ""+i; } private void textBox1_TextChanged(object sender, EventArgs e) { } } } template IDE-generated handler code to add ! [Form1.cs] Form1-class
  122. 122. 122 C# and .NET 1. Introduction 2. C# versus Java : highlights 3. C# data types 4. Defining custom data types 5. Operator Overloading 6. Event driven programming 7. .NET Framework Class Library 8. A GUI in C# 9. A web service in C#
  123. 123. 123 .NET / C# web service - actually part of ASP.NET - uses .asmx file to bind server to code - C# : - web service derives from System.Web.Services.WebService - class must be public, must have public constructor - has [WebService] attribute paramters : - Description : info - Name : default = class name - Namespace : XML-namespace - every exposed service method should have attribute [WebMethod] parameters include : -Description : info -EnableSession : default = false - MessageName : default = method name
  124. 124. 124 .NET / C# web service web server - runs .asmx -file - locates class files referred - loads, runs and manages code client - statically retrieves WSDL document - generates and compiles proxy class - instantiates service proxy - call methods on the proxy
  125. 125. 125 Hello Service Server side Create ASP.NET Web Service project File -> New -> Web Site ASP.NET Web Service template Edit [WebService] attribute (if necessary) Add class logic, give any WS method [WebMethod] attribute Build project Run Project Check if service is running (WSDL-file) http://localhost:1665/WebSite1/?.asmx ? WSDL Invoke method from browser to check proper functioning
  126. 126. 126 Hello Service Service.asmx <%@ WebService Language="C#" CodeBehind="~/App_Code/Service.cs" Class="Service" %>
  127. 127. 127 Hello Service Service.cs using System; using System.Web; using System.Web.Services; using System.Web.Services.Protocols; [WebService(Namespace = "http://tempuri.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class Service : System.Web.Services.WebService { public Service () { //Uncomment the following line if using designed components //InitializeComponent(); } [WebMethod] public string HelloWorld(string e) { return "Hello World there, "+e; } }
  128. 128. 128 Hello Service WSDL (http://localhost:1655/WebSite1/Service.asmx?WSDL)
  129. 129. 129 Hello ServiceService invocation from browser (http://localhost:1655/WebSite1/Service.asmx?op=HelloWorld) Answer : <string>Hello World there, MyName</string>
  130. 130. 130 Hello Service Client side Create Windows Console project (or GUI project ...) Open WS project and add to current solution Add Web Reference -> Browse local host -> Select Web Reference (= namespace for proxy) (Here : HelloService) Add client code -> instantiate proxy object -> call WS methods on proxy
  131. 131. 131 Hello Service using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication3 { class Program { static void Main(string[] args) { HelloService.Service s = new HelloService.Service(); Console.WriteLine(" -> " + s.HelloWorld("Georgie ")); } } } -> Hello World there, Georgie Press any key to continue . . .

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