1. Distributed Systems (236351) Tutorial 1 - Getting Started with Visual Studio C#.NET

2. Staff  Lecturer: Assoc. Prof. Roy Friedman.  Teaching Assistant: Noam Mori. Email: noam@cs.technion.ac.ilnoam@cs.technion.ac.il Office: 325. Office hours: Monday 13:30-14:30. Phone: 04-829-4307. 2

3. Course Info  Home page: http://webcourse.cs.technion.ac.il/236351http://webcourse.cs.technion.ac.il/236351  Three mandatory programming assignments.  Requirements:  Working knowledge of Java / C#  Basic knowledge of OOP concepts  Basic knowledge of network concepts (sockets, protocols)  No textbook, look at the home page for manuals, tutorials and additional resources 3

4. C#  Designer: Anders Hejlsberg (Microsoft) Designer of Turbo Pascal, Visual J++, Delphi (Borland)  C Dynasty: Play on Words C++ increment C by one. C# the musical note half tone above C  Yet another curly bracket programming language Grouping: {} Statements terminated by ";" C operators: ++ % != += && & ^, >>, ?: … C like control: if () … else … for (…; …; …) … break … while (…) … continue … do … while (…) switch (…) … case … default 4

5. Hello World application  Development in Visual Studio is organized around solutions, which contain one or more projects. For this tutorial, we will create a solution with a single C# project.  Creating a New Project In the Visual Studio.NET environment, select File | New | Project from the menu. 5

6. Hello World application cont.  Select Visual C# Projects on the left and then Console Application on the right. 6

7. Hello World application cont.  Specify the name of your project, location in which to create the project and the name of your solution. The project directory will be created automatically by Visual Studio  Click OK and you're on your way! 7

8. Class1.cs using System; //Namespace namespace project_name { class Program { static void Main(string[] args) { Console.WriteLine("Hello World"); } 8

9. Namespaces  Namespaces are used to define scope in C# applications  Multiple source code files can contribute to the same namespace  The using directive permits you to reference classes in the namespace without using a fully qualified name class Class1 { static void Main(string[] args) { System.Console.WriteLine("Hello World"); } 9

10. C# Design Principles  Closer to Java than to C++.  Programmer Protection: Static Typing Strong Typing Array Bounds Checking Garbage Collection Check against using uninitialized variables  Better Java? Developed by Microsoft Compiles to the CLR "Common Language Interface" Support for "unsafe" features, including pointers. 10

11. Object Oriented Purity  Global Variables? No. All variables are defined in functions/classes.  Global Routines? No. All routines (functions) are defined in classes.  Non OO Types? No. Even primitive types belong in the OO hierarchy.  Preprocessor? Yes. 11

12. Value/Reference Semantics  Value Types Simple types: char, int, float, … Enum types Struct types  Reference Types Classes, Interfaces, Delegates public enum Color {Red, Blue, Green} public struct Point { public int x, y; } 12

13. Inheritance Hierarchy  Classes: Single Inheritance Common root: System.Object Unextendable classes: denoted by keyword sealed Static classes: denoted by keyword static No non-static members No instances  Interfaces: Multiple Inheritance hierarchy May be implemented by classes and structs  Structs: No inheritance May implement interfaces 13

14. Accessibility  Five Levels public Unlimited access protected This class and all subclasses private This class only internal protected internal  Default Levels namespace public enum public class private interface public struct private others internal 14

15. Class/Struct Member Kinds  Instance Constructors: similar to C++/Java constructors  Finalizer: Syntax as C++ destructor; semantics as Java finalizer.  Static Constructors: similar to Java static initializers  Constants: value computed at compile time implicitly static  Instance Readonly Fields: with readonly keyword initialized by constructor / static constructor  Instance Fields: like Java/C++  Static Fields: with static keyword  Static Readonly Fields: Initialized by static constructor only  Methods & Static Methods: like Java/C++  Indexers: array access implemented by methods  Properties (and static properties): field access implemented by methods 15

16. Properties  Property: a field implemented with methods  Varieties: read only, write only, read-write  Contextual keywords: get, set, value public struct Window { public int n_read = 0; private string title; public string Title { // read-write property get { // property getter method n_read++; return title; } set { // property setter method if (title == value)// implicit parameter return; title = value; redraw(); } } … { public struct Window { public int n_read = 0; private string title; public string Title { // read-write property get { // property getter method n_read++; return title; } set { // property setter method if (title == value)// implicit parameter return; title = value; redraw(); } } … { Window w = new Window("Initial Title"); Console.WriteLine(w.Title );// increment n_read w.Title = "My Title"; // redraw Window w = new Window("Initial Title"); Console.WriteLine(w.Title );// increment n_read w.Title = "My Title"; // redraw 16