1 comp 144 programming language concepts felix hernandez-campos lecture 39: case study: c# and.net...

COMP 144 Programming Language ConceptsFelix Hernandez-Campos

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Lecture 39: Lecture 39: Case Study: C# and .NETCase Study: C# and .NET

COMP 144 Programming Language ConceptsCOMP 144 Programming Language Concepts

Spring 2002Spring 2002

Felix Hernandez-CamposFelix Hernandez-Campos

April 29April 29

The University of North Carolina at Chapel HillThe University of North Carolina at Chapel Hill


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C# and .NETC# and .NET

• In 2000, Microsoft releases a new language, In 2000, Microsoft releases a new language, C#C#, , heavily influences by Java and C++heavily influences by Java and C++

– Is there anything new from the programming languages Is there anything new from the programming languages point of view?point of view?

• Microsoft is making it the key stone in their new Microsoft is making it the key stone in their new development strategy (development strategy (.NET.NET))

– Big bucks… big evil…Big bucks… big evil…

• Let’s have a brief look at it, so you can put it our Let’s have a brief look at it, so you can put it our resumes or simply laugh at Microsoft, depending on resumes or simply laugh at Microsoft, depending on your point of view about the worldyour point of view about the world

– I’m neutral (yeah, right…)I’m neutral (yeah, right…)


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Hello WorldHello World

public class HelloWorld {public class HelloWorld { public static void main(String[] args) { public static void main(String[] args) { System.out.println(“Hello world!"); System.out.println(“Hello world!"); } }}}

class HelloWorld {class HelloWorld { static void Main(string[] args) { static void Main(string[] args) { System.Console.WriteLine(“Hello world!"); System.Console.WriteLine(“Hello world!"); } }}}

• JavaJava

• C#C#


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Motivation for C#Motivation for C#

• .NET.NET– New development New development

framework that promises to framework that promises to simplify Windows simplify Windows programmingprogramming

» COM/DCOM is hard to COM/DCOM is hard to learnlearn

– Heavy on component Heavy on component orientationorientation

– Language independence Language independence run-time systemrun-time system

» Common Language Run-Common Language Run-time (CLR)time (CLR)

Framework Class LibrariesFramework Class Libraries

WindowsWindows

Common Language RuntimeCommon Language Runtime

C# programsC# programs VB .NETVB .NET


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Common Language RuntimeCommon Language Runtime

• It can execute .NET program in an intermediate It can execute .NET program in an intermediate representation, the representation, the Common Language InterfaceCommon Language Interface (CLI)(CLI)

• CLR is designed to work well in a multi-language CLR is designed to work well in a multi-language environmentenvironment

– Java Virtual Machines is rather Java-orientedJava Virtual Machines is rather Java-oriented– CLR is supposed to work well with imperative CLR is supposed to work well with imperative

programming languages (programming languages (e.g.e.g., C, Pascal) and statically , C, Pascal) and statically typed object oriented languages (typed object oriented languages (e.g.e.g., C#, Eiffel), C#, Eiffel)

– Many language have compilers for CLR at different stages Many language have compilers for CLR at different stages of development, including Python, Perl, Scheme, Haskell, of development, including Python, Perl, Scheme, Haskell, Prolog,…Prolog,…


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Motivation for C#Motivation for C#

• Rapid application development (RAD)Rapid application development (RAD)– Visual development tools/languages such as Visual Basic Visual development tools/languages such as Visual Basic

and Delphi, are very popular and usefuland Delphi, are very popular and useful» Remember Java Beans lectureRemember Java Beans lecture

– C# is optimized for such development modelC# is optimized for such development model

• Platform-independencePlatform-independence– CLR and CLICLR and CLI

• Access to platform-native resourcesAccess to platform-native resources– A more direct approach than the one taken by Java Native A more direct approach than the one taken by Java Native

Interface (JNI)Interface (JNI)


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C# SyntaxC# SyntaxComparison with JavaComparison with Java

• If/then/elseIf/then/else

int i = 0;int i = 0;if (i == 0) {if (i == 0) { i = 1; i = 1;} else {} else { i = 2; i = 2;}}

int i = 0;int i = 0;if (i == 0) {if (i == 0) { i = 1; i = 1;} else {} else { i = 2; i = 2;}}

JavaJava C#C#


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C# SyntaxC# Syntax

• SwitchSwitch

int i = 0;int i = 0;switch (i) {switch (i) { case 0: case 0:

i = 1; i = 1; break;break;

case 1: case 1: i = 2;i = 2;break;break;

default: default:i = -1; i = -1; break;break;

}}

int i = 0;int i = 0;switch (i) {switch (i) { case 0: case 0:

i = 1;i = 1;break;break;

case 1: case 1:i = 2; i = 2; break;break;

default: default:i = -1; i = -1; break;break;

}}

JavaJava C#C#


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C# SyntaxC# Syntax

• WhileWhile

• Do/WhileDo/While

int i = 0;int i = 0;while (i++ < 10) {while (i++ < 10) {}}

int i = 0;int i = 0;while (i++ < 10) {while (i++ < 10) {}}

JavaJava C#C#

int i = 0;int i = 0;do {do {} while (i++ < 10);} while (i++ < 10);

int i = 0;int i = 0;do {do {} while (i++ < 10);} while (i++ < 10);

JavaJava C#C#


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C# SyntaxC# Syntaxforeachforeach

import java.util.Vector;import java.util.Vector;public static int sum(Vector v) {public static int sum(Vector v) { int sum = 0; int sum = 0; for (int j = 0; j < v.size(); j++) { for (int j = 0; j < v.size(); j++) { Integer i = (Integer)v.elementAt(j); Integer i = (Integer)v.elementAt(j); sum = sum + i.intValue(); sum = sum + i.intValue(); } } return sum; return sum;}}

using System.Collections;using System.Collections;static int SumList(ArrayList theList) {static int SumList(ArrayList theList) { int sum = 0; int sum = 0; foreachforeach (int j (int j inin theList) { theList) { sum = sum + j; sum = sum + j; } } return sum; return sum;}}

JavaJava

C#C#


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C# SyntaxC# Syntax

• Break/ContinueBreak/Continue

• ReturnReturn

int i = 0;int i = 0;while (i++ < 10) {while (i++ < 10) { if (i < 5) continue; if (i < 5) continue; break; break;}}

JavaJava

public void public void returnNothing() {returnNothing() { return; return;}}public int returnOne() {public int returnOne() { return 1; return 1;}}

int i = 0;int i = 0;while (i++ < 10) {while (i++ < 10) { if (i < 5) continue; if (i < 5) continue; break; break;}}

C#C#

public void public void returnNothing() {returnNothing() { return; return;}}public int returnOne() {public int returnOne() { return 1; return 1;}}


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C# SyntaxC# Syntax

• Object instantiationObject instantiation

• Exclusive accessExclusive access

Something s = Something s = new Something();new Something();

JavaJava

synchronized(this) {synchronized(this) { // do something// do something}}

Something s = Something s = new Something();new Something();

C#C#

lock(this) {lock(this) { // do something// do something}}


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C# SyntaxC# Syntaxtry/catch/finallytry/catch/finally

try {try { throw new SampleException(); throw new SampleException();} catch (SampleException ex) {} catch (SampleException ex) {} finally {} finally {}}

try {try { throw new SampleException(); throw new SampleException();} catch (SampleException ex) {} catch (SampleException ex) {} finally {} finally {}}

try {try { throw new SampleException(); throw new SampleException();} catch {} finally {} catch {} finally {}}

JavaJava

C#C#

• catchcatch clause is optional clause is optional

• catchcatch argument is optional argument is optional

• No No throwsthrows keyword keyword


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C# SyntaxC# Syntax

• Class definitionClass definition

• Interface definitionInterface definition

• Interface implementationInterface implementation

class Foo extends Bar {class Foo extends Bar {......}}

JavaJava

interface IFoo extends IBar {interface IFoo extends IBar {......}}

class Foo extends Bar {class Foo extends Bar {......}}

C#C#

interface IFoo : IBar {interface IFoo : IBar {......}}

class Foo implements IFoo, class Foo implements IFoo, IBaz {IBaz {......}}

class Bar: IFoo, IBaz {class Bar: IFoo, IBaz {}}


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Other C# FeaturesOther C# Features

• C# provides Java-style garbage collectionC# provides Java-style garbage collection

• C# implements a Java- and Delphi-style C# implements a Java- and Delphi-style value/reference-type systemvalue/reference-type system

– Variables of primitive types also act like objects (unlike Variables of primitive types also act like objects (unlike Java primitive objects)Java primitive objects)

Integer iobj = new Integer(12);Integer iobj = new Integer(12);System.out.println(iobj.toString());System.out.println(iobj.toString());

Console.WriteLine(12.ToString());Console.WriteLine(12.ToString());

JavaJava

C#C#


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• EnumerationsEnumerationsenum description: ulong {enum description: ulong {

Good, Good, Bad, Bad, Ugly Ugly

};};

• Properties (forced getter and setters)Properties (forced getter and setters)TextBlock tb;TextBlock tb;

if (tb.backgroundColor == Color.green) { if (tb.backgroundColor == Color.green) {

// "get" is called for comparison// "get" is called for comparison

tb.backgroundColor = Color.red; tb.backgroundColor = Color.red; // "set" is called// "set" is called

} else {} else {

tb.backgroundColor = Color.blue; tb.backgroundColor = Color.blue; // "set“ is called// "set“ is called

}}


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• Get/setGet/setpublic class TextBlock {public class TextBlock {

// Assume Color is an enum// Assume Color is an enum

private Color _bgColor;private Color _bgColor;

private Color _fgColor;private Color _fgColor;

public Color backgroundColor {public Color backgroundColor { getget { {

return _bgColor;return _bgColor;

}} setset { {

_bgColor = value;_bgColor = value; } } //... and so on...//... and so on... } }

}}


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• DelegatesDelegates– Safe method reference (solved with interfaces in Java)Safe method reference (solved with interfaces in Java)

delegate int Comparator(object a, object b);delegate int Comparator(object a, object b);

class Quicksort {class Quicksort { static void sort(Comparator c, object[] static void sort(Comparator c, object[] objectsToSort) { objectsToSort) { // ... quicksort logic leading to a comparison// ... quicksort logic leading to a comparison if (c(objectsToSort[left], if (c(objectsToSort[left],

objectsToSort[pivot]) > 0) {objectsToSort[pivot]) > 0) {

// recursive call...// recursive call...

} else { } else { // ...and so on...// ...and so on... } }; } };


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ReferencesReferences

• Perry, Perry, C#, the natural progressionC#, the natural progression– http://www.javaworld.com/javaworld/jw-08-2000/jw-0804http://www.javaworld.com/javaworld/jw-08-2000/jw-0804

-itw-csharp.html-itw-csharp.html

• Johnson, Johnson, C#: A language alternative or just J--?C#: A language alternative or just J--?– http://www.javaworld.com/javaworld/jw-08-2000/jw-0804http://www.javaworld.com/javaworld/jw-08-2000/jw-0804

-itw-csharp.html-itw-csharp.html

• Meijer and Gough, Meijer and Gough, Technical Overview of the Technical Overview of the Common Language RuntimeCommon Language Runtime

– http://research.microsoft.com/~emeijer/Papers/CLR.http://research.microsoft.com/~emeijer/Papers/CLR.pdfpdf

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