Lecture 39: Case Study: C# and .NET

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1 Lecture 39: Case Study: C# and .NET
The University of North Carolina at Chapel Hill COMP 144 Programming Language Concepts Spring 2002 Lecture 39: Case Study: C# and .NET Felix Hernandez-Campos April 29 COMP 144 Programming Language Concepts Felix Hernandez-Campos

2 C# and .NET In 2000, Microsoft releases a new language, C#, heavily influences by Java and C++ Is there anything new from the programming languages point of view? Microsoft is making it the key stone in their new development strategy (.NET) Big bucks… big evil… Let’s have a brief look at it, so you can put it our resumes or simply laugh at Microsoft, depending on your point of view about the world I’m neutral (yeah, right…) COMP 144 Programming Language Concepts Felix Hernandez-Campos

3 Hello World Java C# public class HelloWorld {    public static void main(String[] args) {       System.out.println(“Hello world!");    } } class HelloWorld {    static void Main(string[] args) {       System.Console.WriteLine(“Hello world!");    } } COMP 144 Programming Language Concepts Felix Hernandez-Campos

4 Framework Class Libraries Common Language Runtime
Motivation for C# .NET New development framework that promises to simplify Windows programming COM/DCOM is hard to learn Heavy on component orientation Language independence run-time system Common Language Run-time (CLR) C# programs VB .NET Framework Class Libraries Common Language Runtime Windows COMP 144 Programming Language Concepts Felix Hernandez-Campos

5 Common Language Runtime
It can execute .NET program in an intermediate representation, the Common Language Interface (CLI) CLR is designed to work well in a multi-language environment Java Virtual Machines is rather Java-oriented CLR is supposed to work well with imperative programming languages (e.g., C, Pascal) and statically typed object oriented languages (e.g., C#, Eiffel) Many language have compilers for CLR at different stages of development, including Python, Perl, Scheme, Haskell, Prolog,… COMP 144 Programming Language Concepts Felix Hernandez-Campos

6 Motivation for C# Rapid application development (RAD)
Visual development tools/languages such as Visual Basic and Delphi, are very popular and useful Remember Java Beans lecture C# is optimized for such development model Platform-independence CLR and CLI Access to platform-native resources A more direct approach than the one taken by Java Native Interface (JNI) COMP 144 Programming Language Concepts Felix Hernandez-Campos

7 C# Syntax Comparison with Java
If/then/else Java C# int i = 0; if (i == 0) {    i = 1; } else {    i = 2; } int i = 0; if (i == 0) {    i = 1; } else {    i = 2; } COMP 144 Programming Language Concepts Felix Hernandez-Campos

8 C# Syntax Switch C# Java int i = 0; switch (i) { case 0:
break;    case 1:       i = 2; break;    default: i = -1;     break; } int i = 0; switch (i) {    case 0:       i = 1; break;    case 1: i = 2; break;    default: i = -1; break; } COMP 144 Programming Language Concepts Felix Hernandez-Campos

9 C# Syntax While Do/While C# Java int i = 0; while (i++ < 10) { }
int i = 0; do { } while (i++ < 10); int i = 0; do { } while (i++ < 10); COMP 144 Programming Language Concepts Felix Hernandez-Campos

10 C# Syntax foreach Java import java.util.Vector; public static int sum(Vector v) {    int sum = 0;    for (int j = 0; j < v.size(); j++) {         Integer i = (Integer)v.elementAt(j);          sum = sum + i.intValue();    }    return sum; } C# using System.Collections; static int SumList(ArrayList theList) {    int sum = 0;    foreach (int j in theList) {       sum = sum + j;    }    return sum; } COMP 144 Programming Language Concepts Felix Hernandez-Campos

11 C# Syntax Break/Continue Return Java C#
int i = 0; while (i++ < 10) {    if (i < 5) continue;    break; } int i = 0; while (i++ < 10) {    if (i < 5) continue;    break; } public void returnNothing() {    return; } public int returnOne() {    return 1; } public void returnNothing() {    return; } public int returnOne() {    return 1; } COMP 144 Programming Language Concepts Felix Hernandez-Campos

12 C# Syntax Object instantiation Exclusive access Java C# Something s =
new Something(); Something s = new Something(); synchronized(this) {    // do something } lock(this) {    // do something } COMP 144 Programming Language Concepts Felix Hernandez-Campos

13 C# Syntax try/catch/finally
Java try {    throw new SampleException(); } catch (SampleException ex) { } finally { } C# try {    throw new SampleException(); } catch (SampleException ex) { } finally { } try {    throw new SampleException(); } catch {} finally { } catch clause is optional catch argument is optional No throws keyword COMP 144 Programming Language Concepts Felix Hernandez-Campos

14 C# Syntax Class definition Interface definition
Interface implementation Java C# class Foo extends Bar { ... } class Foo extends Bar { ... } interface IFoo extends IBar { ... } interface IFoo : IBar { ... } class Foo implements IFoo, IBaz { ... } class Bar: IFoo, IBaz { } COMP 144 Programming Language Concepts Felix Hernandez-Campos

15 Other C# Features C# provides Java-style garbage collection
C# implements a Java- and Delphi-style value/reference-type system Variables of primitive types also act like objects (unlike Java primitive objects) Java Integer iobj = new Integer(12); System.out.println(iobj.toString()); C# Console.WriteLine(12.ToString()); COMP 144 Programming Language Concepts Felix Hernandez-Campos

16 Other C# Features Enumerations Properties (forced getter and setters)
enum description: ulong {    Good,    Bad,    Ugly }; Properties (forced getter and setters) TextBlock tb; if (tb.backgroundColor == Color.green) { // "get" is called for comparison    tb.backgroundColor = Color.red;  // "set" is called } else {    tb.backgroundColor = Color.blue;  // "set“ is called } COMP 144 Programming Language Concepts Felix Hernandez-Campos

17 Other C# Features Get/set public class TextBlock {
   // Assume Color is an enum private Color _bgColor; private Color _fgColor;    public Color backgroundColor {   get {          return _bgColor;      }   set { _bgColor = value;   }    //... and so on...  } } COMP 144 Programming Language Concepts Felix Hernandez-Campos

18 Other C# Features Delegates
Safe method reference (solved with interfaces in Java) delegate int Comparator(object a, object b); class Quicksort {    static void sort(Comparator c, object[]    objectsToSort) {       // ... quicksort logic leading to a comparison          if (c(objectsToSort[left], objectsToSort[pivot]) > 0) {             // recursive call...          } else { // ...and so on...    } }; COMP 144 Programming Language Concepts Felix Hernandez-Campos

19 References Perry, C#, the natural progression
Johnson, C#: A language alternative or just J--? Meijer and Gough, Technical Overview of the Common Language Runtime COMP 144 Programming Language Concepts Felix Hernandez-Campos