1. 1 st Semester 2005 1 Module2 Basic C# Concept อภิรักษ์ จันทร์สร้าง Aphirak Jansang aphirak.j@ku.ac.th http://www.cpe.ku.ac.th/~aphirak Computer Engineering Department Kasetsart University, Bangkok THAILAND

2. 1 st Semester 2005 2 Outline  C# Overview  Variable and Constant  Expression  Statement

3. 1 st Semester 2005 3 Simple C# program structure Your Class Name Your declaration part Your statements Your Namespace Name C# Overview

4. 1 st Semester 2005 4 Naming Guidelines  Letters, digits, underscores(_)  First character  letter  Can be long (63 char)  Reserved words (keywords) are not allowed *** Case Sensitive *** Example KU65 ≠ kU65 ≠ku65 KU65 ≠ kU65 ≠ ku65 C# Overview

5. 1 st Semester 2005 5 Built-in Namespace: System Console Console class can be used for Displaying Displaying information on the screenSystem.Console.Write(”HelloWorld!”);System.Console.WriteLine(”HelloWorld!”); Retrieving Retrieving information from the user String ch; ch = System.Console.Readline(); C# Overview

6. 1 st Semester 2005 6 How to Comment Code in C# 1 2

7. 1 st Semester 2005 7 Summary C# Program Overview  Namespace Class  Main() C# Overview

8. 1 st Semester 2005 8 Outline  C# Overview  Variable and Constant  Expression  Statement

9. 1 st Semester 2005 9 Basic uses Declaration Part  Variable  Constant Variable & Constant

10. 1 st Semester 2005 10 What is Variable? Variables are used to store “data.” “They must be declared before used” Variable & Constant

11. 1 st Semester 2005 11 C# Declaration Location Declaration Part Here Variable & Constant

12. 1 st Semester 2005 12 C# Variable Declaration  Syntax: ;  Example:  We can also assign its initial value. E.g., int radius; double area; int a,b,c; bool isokay; int k = 200; bool done = false; Variable & Constant

13. 1 st Semester 2005 13 C# Basic Data Type  int Integer ( -2147483648 to 2147483647)  double Floating-point ( )  bool Boolean values, true and false  char a Unicode character (’A’ ’B’)  string string of Unicode characters (”StarsIII”) Variable & Constant

14. 1 st Semester 2005 14 Example: Variable Declaration Variable & Constant

15. 1 st Semester 2005 15 Basic uses Declaration Part  Variable  Constant Variable & Constant

16. 1 st Semester 2005 16 C# Constant Declaration  Syntax: const = ;  Example: const int radius = 15; const double area=1.5; const bool isokay=true; const string movie=”StarWarIII”; Variable & Constant

17. 1 st Semester 2005 17 Outline  C# Overview  Variable and Constant  Expression  Statement

18. 1 st Semester 2005 18 Arithmetic Expression in C#  Operators + - * / % (remainder after division)  Example 11 + 5  16 11 / 2  5.5 11 % 2  1 5.0 % 2.2  0.6Expression

19. 1 st Semester 2005 19 Precedence rules for Arithmetic Operators 1.( ) parentheses 2.*, /, % 3.+ – 4.If equal precedence, left to right Example int Width,High; Width=10*5+(16 * 12)/5; High= (16+5)+20%2;

20. 1 st Semester 2005 20 Outline  C# Overview  Variable and Constant  Expression  Statement

21. 1 st Semester 2005 21 C# Statement LocationStatementsHereStatement

22. 1 st Semester 2005 22 C# Statement Types  Assignment Statement  Input Statement  Output StatementStatement

23. 1 st Semester 2005 23 Assignment Statement "put"  To "put" a value in the memory space allocated to a variable equal sign (=)  Use the equal sign (=) when making assignments.  Syntax: = ; = ; int Width,High; Width=10;High=5; int Width = 10; int High = 5; Statement

24. 1 st Semester 2005 24 Example: Assignment StatementStatement

25. 1 st Semester 2005 25 C# Statement Types  Assignment Statement  Input Statement  Output StatementStatement

26. 1 st Semester 2005 26 Input Statement  Console.ReadLine()  Return string Use to get the input from user  Convert string to other data type int.Parse() Convert string to integer double.Parse() Convert string to double Example string yourname; yourname = Console.ReadLine(); Statement

27. 1 st Semester 2005 27 Example: Input Statement Ex1: string myname; myname = Console.ReadLine(); Ex2: int Width,High; string temp1; temp1 = Console.ReadLine(); Width = int.Parse(temp1); temp1 = Console.ReadLine(); Width = int.Parse(temp1); Statement

28. 1 st Semester 2005 28 C# Statement Types  Assignment Statement  Input Statement  Output StatementStatement

29. 1 st Semester 2005 29 Output Statement  Console.WriteLine(VariableName)  Display variable value in some position of string  Output Formatting Example1 Console.WriteLine(”Hello {0}, {1}”, ps0, ps1); Example2 double salary=12000; Console.WriteLine("My salary is {0:f}.", salary); More information about formatting *http://msdn.microsoft.com/library/en-us/csref/html/vclrfFormattingNumericResultsTable.asp Statement

30. 1 st Semester 2005 30 Summary  C# Overview  Variable and Constant  Expression  Statement