Platforms and tools for Web Services and Mobile Applications Introduction to C# Bent Thomsen Aalborg University 3rd and 4th of June 2004

Introduction to C# What is C# Java like language from Microsoft Object Orientated Language Derived from C++ Has the power of C++ and the simplicity of Visual Basic Part of Microsoft.NET framework If you are serious about.Net you need to learn C#

Introduction to C# Can only run on Windows OS Cross Language Able to use objects created in C++.NET and Visual Basic.NET and all the other.NET Languages (or not) Cross Platform What is C# (con’t)

Introduction to C# What do you need? –Windows OS Machine. Windows 2000, XP or 2003 –Microsoft.NET SDK –Text Editor Save files with a.cs extension Getting started with C#

Introduction to C# What about a development environment? –Visual C++ from Visual Studio 6.0 Requires registry tweaking –Visual Studio.NET –3 rd Party software Emacs and XEmacs Borland Getting started with C# (con’t)

C# vs. The World Compilation Process CPU code csc JIT.cs Source Code.exe.dll Microsoft Intermediate Language (MSIL) CLS Compliant Languages How does C# work?

C# vs. The World Common Language Runtime (CLR) –Provides an execution engine for developers code Code management (loading and execution) Memory management Garbage Collection Verification of type safety Enforcement of code access security Interoperation between managed code, COM objects, and pre-existing DLLs How does C# work? (con’t)

C# vs. The World Hello world using System; class HelloWorld { public static void Main() { Console.WriteLine(“Hello World!"); } >csc HelloWorld.cs >Hello World! The Language (con’t)

C# vs. The World Properties public class button { private string caption; public string Caption { get { return caption; } set { if (value != null) caption = value; } button b = new button(); b.Caption = “abc” string s = b.Caption; The Language (con’t)

C# vs. The World Parameter Passing The Language (con’t) By Value public static void Swap(ref int x, ref int y) { int z = x; x = y; y = z; } By Reference

C# vs. The World Pointers –Not recommended for use public struct Node { public int value; public unsafe Node* next; } The Language (con’t) public unsafe class A {... public class A { public unsafe void B (char *p) {...

C# vs. The World The Language (con’t) Boxing / Unboxing –Allows value types to be converted to and from objects automatically ArrayList list = new ArrayList(); int z = 100; list.Add(1); list.Add(13.12); list.Add(z); //integers are automatically boxed //when they are added to the list

C# vs. The World The Language (con’t) Delegates –Basically a type-safe object orientated function pointer delegate void simpleDelegate(); Class Test { static void F() { System.Console.Writeline(“Test.F”); } static void main (){ simpleDelegate d = new simpleDelegate(F); d(); }

C# vs. The World The Language (con’t) Delegates (con’t) void multiCall (simpleDelegate d, int count) { for (int i=0; i<count; i++){ d(); }

C# vs. The World The Language (con’t) Versioning Class B y(); Class A x(); v.1 Class A x(); y(); v.2 Class B y(); Which one to use?

C# vs. The World Versioning –C# requires developers to clearly state their intent Use of the keyword ‘new’ and ‘override’ Class Derived B { new public void x () {... Class Derived B { public override void x () {... The Language (con’t)

C# vs. The World Libraries The Language (con’t) Few core libraries Uses the libraries from the.NET framework Threading, Collection, XML, ADO+, ASP+, GDI+ & WinForms libraries

C# vs. The World Comparison of C# syntax with Java and C++ Similarities Single rooted class hierarchy Similar keywords (derived from C++) Virtual Machine & IL/CLR Garbage Collection No global methods Interface, no Multiple inheritance Exception handling

C# vs. The World Comparison of C# syntax with Java and C++ Differences Syntax and Keywords not from C++ Properties, Delegates, Boxing, Pointers, Libraries, etc. Preprocessor Directives

C# vs. The World Easy to learn, similar to both C++ and JAVA Can use existing pool of C++ and Visual Basic programmers. Can use components from.NET Syntactical Sugar C# Advantages

C# vs. The World Only runs on Windows machines Limited choice in development environment Locked into Microsoft compatibility Not extensively tested Not enough maturity time C# Disadvantages