Building non-windows applications (programs that only output to the command line and contain no GUI components).

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1 C# and.net (1) Acknowledgements and copyrights: these slides are a result of combination of notes and slides with contributions from: Michael Kiffer, Arthur Bernstein, Philip Lewis, Hanspeter Mφssenbφck, Hanspeter Mφssenbφck, Wolfgang Beer, Dietrich Birngruber, Albrecht Wφss, Mark Sapossnek, Bill Andreopoulos, Divakaran Liginlal, Michael Morrison, Anestis Toptsis, Deitel and Associates, Prentice Hall, Addison Wesley, Microsoft AA. They serve for teaching purposes only and only for the students that are registered in CSE4413 and should not be published as a book or in any form of commercial product, unless written permission is obtained from each of the above listed names and/or organizations. 1

2 Building non-windows applications (programs that only output to the command line and contain no GUI components). 2

3 Or can use any text editor and type your program (good for when new to programming in general but not really for now) Upon typing the., VS gives options available 3

4 The final program 4

5 Compile and Run Run Compile (and produce.exe) 5

6 The output 6

7 The C# (and.net in general) API Choose 7

8 / System is a major namespace for C# 8

9 Example of a C# console application 9

10 Start a new console application then Add class Employee. (you can add the class via the wizard, or by manually typing it). 10

11 Add fields (instance variables), methods, etc. (You can add them via the wizard, or by manually typing them). 11

12 Can declare using the wizard or just manually inside the code. 12

13 Creating a property 13

14 Class View (after writing the code..) Main() execution starts here Ctor and methods properties Instance variables 14

15 using System; namespace ConsoleApplication2 { class Class1 { [STAThread] static void Main(string[] args) { Console.Write( "Enter name : "); string thename = Console.ReadLine(); } Call method raise() } } Console.Write( "Enter salary : " ); string thesalary = Console.ReadLine(); The code Read until end of line. Console.WriteLine( "name = " + thename + " salary = " + thesalary); double thesalarydouble = Convert.ToDouble(theSalary); Employee e = new Employee(theName, thesalarydouble); Console.WriteLine( "e:: " + e.tostring()); e.raise(10); Console.WriteLine( "e:: " + e.tostring()); e.name = Another name ; e.salary = 25000; Console.WriteLine( "e:: " + e.tostring()); Use properties Convert string to double. Call ctor 15

16 using System; Employee.cs namespace ConsoleApplication2 { /// <summary> Class Employee /// starts here /// </summary> public class Employee { public Employee() { Default constructor // // TODO: Add constructor logic here // } private double salary; private string name; Employee.cs is the name of the file that holds the source code for class Employee. All C# source files have the extension.cs 16

17 public double Salary { set { salary = value; } get { return salary; } } public string Name { get { return name; } set { name = value; } } Property Salary Property Name 17

18 public Employee (string name, double salary) { this.name = name; this.salary = salary; } constructor / public void raise( double percent ) { this.salary = this.salary*(1+percent/100); } public override string ToString ( ) { return "salary = " + salary + " name = " + name; } } } The reserved word override is used for every method that overrides a method. 18

19 C# Developed at Microsoft by a team led by Anders Hejlsberg and Scott Wiltamuth (June 2000) Event driven, object oriented, visual programming language. Based on C, C++ and Java. Incorporated into.net platform Web based applications can be distributed Devices and desktop computers Programs that can be accessed by anyone through any device Allows communicating with different computer languages (any language that is supported by.net). 19

20 Visual Studio.NET Integrated Development Environment (IDE) Overview location bar navigation buttons hidden window recent projects Start Page links buttons Start Page in Visual Studio.NET. 20

21 .NET Framework and the Common Language Runtime.NET Framework Heart of.net Manages and executes applications and Web services Provides security, memory management and other programming capabilities Includes Framework class library (FCL) Pre-packaged classes ready for reuse Used by any.net language (VB, C#, C++, J#, etc ) Common Language Specification (CLS), is a specification that all languages that run under.net should conform to. Submitted to European Computer Manufacturers Association to make the framework easily converted to other platforms Executes programs by Common Language Runtime (CLR) 21

22 .NET Framework and the Common Language Runtime (CLR) Common Language Runtime (CLR). Central part of framework Compilation process Two compilations take place 1. Programs compiled to Intermediate Language (IL). (IL is like Java s bytecode). 2. IL code is translated into machine code for a particular platform 22

23 JVM (Java) vs CLR (.NET) : multiple platforms vs multiple languages. 23

24 What you need to develop C# programs Either Visual Studio.NET IDE, or The.NET SDK (currently version 1.1) Command line development About 100 MB download 24

25 How to get and install the.net SDK [currently version 1.1] (for C# development without using Visual Studio. Normally you will not do this if you have Visual Studio) search for.net Framework SDK 3. and get a2ca f41-a333c6b9181d&displaylang=en You need also the Microsoft.NET Framework Version 1.1 Redistributable Package : 3-F D1E7CF3A3&displaylang=en Note: If you have already installed Microsoft Visual Studio.NET 2003, you do not need to install the.net Framework SDK separately. Visual Studio.NET 2003 includes the SDK. 25

26 C# constructs C# has all the standard structured programming constructs (such as if, while, for, break, continue, switch, etc) and they all have the same syntax as in Java. Also C# has method overloading, the same way as in Java. In a typical C# program we have several classes (in the same sense as in Java) and if the program is a Console Application (i.e., non-windows) one class that contains Main() the method that starts execution. Each class may have one or more constructors (same as in Java). C# has the this keyword, with the same meaning as in Java. (but not for using it as this( ) inside constructors.) 26

27 C# constructs / Arrays are defined and used as in Java (but there are some additional variations in C#). int[] x;// declare reference to an array x = new int[ 10 ]; // locate an array of size 10. The foreach keyword can be used to traverse arrays (in addition to the standard for-loop). 27

28 1 // ForEach.cs 2 // Demonstrating for/each structure. 3 using System; 4 5 class ForEach 6 { 7 // main entry point for the application 8 static void Main( string[] args ) 9 { 10 int[,] gradearray = { { 77, 68, 86, 73 }, 11 { 98, 87, 89, 81 }, { 70, 90, 86, 81 } }; int lowgrade = 100; foreach ( int grade in gradearray ) 16 { 17 if ( grade < lowgrade ) 18 lowgrade = grade; 19 } Console.WriteLine( "The minimum grade is: " + lowgrade ); 22 } 23 } The minimum grade is: 68 ForEach.cs Use the foreach loop to examine each element in the array If the current array element is smaller than lowgrade, set lowgrade to contain the value of the current element 28

29 Properties (one feature that Java does not have) Public properties allow clients to: Get (obtain the values of) private data Set (assign values to) private data Get accessor Controls formatting of data Set accessor Ensure that the new value is appropriate for the data member 29

30 How to use properties int x = time.hour, where time is an object (of a class Time, probably), is equivalent to int x = time.gethour() of the Java getter method. time.hour = 5, is equivalent to time.sethour(5), assuming the sethour(int) method was available. 30

31 Cont.. Operator overloading C# contains many operators (such as + and - ) that are defined for some primitive types It is often useful to use operators with user-defined types (e.g., a complex number class) Operator notation may often be more intuitive than method calls C# allows programmers to overload operators to make them sensitive to the context in which they are used 31

32 Operator Overloading Methods define the actions to be taken for the overloaded operator They are in the form: public static ReturnType operator operatorto-be-overloaded( arguments ) These methods must be declared public and static The return type is the type returned as the result of evaluating the operation The keyword operator follows the return type to specify that this method defines an operator overload The last piece of information is the operator to be overloaded (such as +, -, *, etc.) If the operator is unary, one argument must be specified, if the operator is binary, then two, etc. 32

33 1 // ComplexNumber.cs 2 // Class that overloads operators for adding, subtracting 3 // and multiplying complex numbers. 4 5 public class ComplexNumber 6 { 7 private int real; 8 private int imaginary; 9 10 // default constructor 11 public ComplexNumber() {} // constructor 14 public ComplexNumber( int a, int b ) 15 { Property Real provides access to the real part of the complex number 16 Real = a; 17 Imaginary = b; Class ComplexNumber definition 18 } // return string representation of ComplexNumber 21 public override string ToString() 22 { 23 return "( " + real + 24 ( imaginary < 0? " - " + ( imaginary * -1 ) : 25 " + " + imaginary ) + "i )"; 26 } // property Real 29 public int Real 30 { 31 get 32 { 33 return real; 34 } 35 ComplexNumber.cs 33

34 36 set 37 { 38 real = value; 39 } } // end property Real // property Imaginary 44 public int Imaginary 45 { 46 get 47 { 48 return imaginary; 49 } set 52 { 53 imaginary = value; 54 } } // end property Imaginary // overload the addition operator 59 public static ComplexNumber operator + ( 60 ComplexNumber x, ComplexNumber y ) 61 { 62 return new ComplexNumber( 63 x.real + y.real, x.imaginary + y.imaginary ); 64 } 65 ComplexNumber.cs Overload the addition (+) operator for ComplexNumbers. Property Imaginary provides access to the imaginary part of a complex number 34

35 66 // provide alternative to overloaded + operator 67 // for addition 68 public static ComplexNumber Add( ComplexNumber x, 69 ComplexNumber y ) 70 { 71 return x + y; 72 } 74 // overload the subtraction operator 75 public static ComplexNumber operator - ( 76 ComplexNumber x, ComplexNumber y ) 77 { 78 return new ComplexNumber( 79 x.real - y.real, x.imaginary - y.imaginary ); 80 } // provide alternative to overloaded - operator 83 // for subtraction 84 public static ComplexNumber Subtract( ComplexNumber x, 85 ComplexNumber y ) 86 { 87 return x - y; 88 } 90 // overload the multiplication operator 91 public static ComplexNumber operator * ( 92 ComplexNumber x, ComplexNumber y ) 93 { 94 return new ComplexNumber( 95 x.real * y.real - x.imaginary * y.imaginary, 96 x.real * y.imaginary + y.real * x.imaginary ); 97 } ComplexNumber.cs Method Subtract provides an alternative to the subtraction operator Overloads the multiplication (*) operator for ComplexNumbers Method Add provides an alternative to the addition operator Overload the subtraction (-) operator for ComplexNumbers 35

36 98 ComplexNumber.cs 99 // provide alternative to overloaded * operator 100 // for multiplication 101 public static ComplexNumber Multiply( ComplexNumber x, 102 ComplexNumber y ) 103 { 104 return x * y; 105 } } // end class ComplexNumber Method Multiply provides an alternative to the multiplication operator 36