1 st Semester Module2 Basic C# Concept อภิรักษ์ จันทร์สร้าง Aphirak Jansang Computer Engineering Department Kasetsart University, Bangkok THAILAND

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

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

1 st Semester 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

1 st Semester 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

1 st Semester How to Comment Code in C# 1 2

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

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

1 st Semester Basic uses Declaration Part  Variable  Constant Variable & Constant

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

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

1 st Semester 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

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

1 st Semester Example: Variable Declaration Variable & Constant

1 st Semester Basic uses Declaration Part  Variable  Constant Variable & Constant

1 st Semester 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

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

1 st Semester Arithmetic Expression in C#  Operators + - * / % (remainder after division)  Example  / 2  % 2  % 2.2  0.6Expression

1 st Semester 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;

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

1 st Semester C# Statement LocationStatementsHereStatement

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

1 st Semester 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

1 st Semester Example: Assignment StatementStatement

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

1 st Semester 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

1 st Semester 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

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

1 st Semester 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 * Statement

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