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C# Basics

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Basics of C# programming

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C# Basics

  1. 1. © Rays Technologies 1 C# BASICS www.sunilos.com www.raystec.com 10/14/16
  2. 2. 10/14/16 © Rays Technologies 2 C# Object Oriented Programming Language Basic unit of C# is Object An Object is an instances of Class Class defines structure/skeleton of an Object The basic building blocks of C# is a Class so a C# program is nothing but a class
  3. 3. 10/14/16 © Rays Technologies 3 C# Class contains methods and variables Variables contains values Methods perform operations A Class should have default method ‘Main’ that is entry point of an application
  4. 4. 10/14/16 © Rays Technologies 4 Program Procedural Language int i = 5 //global variable void main(){ .. a(); } void a(int k){ int j = 0; //local variable .. }
  5. 5. 10/14/16 © Rays Technologies 5 Procedural Language Library Library Program 1 Program 2 Program 3 Program 4
  6. 6. 10/14/16 © Rays Technologies 6 Class C# Language int i = 5 //global variable void main(){ .. a(); } void a(int k){ int j = 0; //local variable .. }
  7. 7. 10/14/16 © Rays Technologies 7 C # Library Namespace Class 1 Class 2 Class 3 Class 4
  8. 8. 10/14/16 © Rays Technologies 8 C# Application ApplicationApplication Napspace 1 Namespace 2 Namespace 3 Namspace 4
  9. 9. 10/14/16 © Rays Technologies 9 C# Program is a Class public class HelloCSharp{ ……. } A class may contain multiple variables and methods A Class should have default ‘Main’ method that is an entry point for an application
  10. 10. 10/14/16 © Rays Technologies 10 My First Program - HelloCSharp  using System;  public class HelloCSharp { o public static void Main() { o String name = “Vijay”; o Console.WriteLine(“Hello” + name); o }  }  using, public, class, static, and void are keywords  Keywords are always written in small letters
  11. 11. 10/14/16 © Rays Technologies 11 Compile & Run Compile o csc HelloCSharp.cs o It will generate HelloCSharp.exe Run o HelloCSharp
  12. 12. 10/14/16 © Rays Technologies 12 Keywords class – is used to define a class public – Access modifier shows accessibility of a class or variable or method to other C# classes. There are 3 access modifiers public, protected and private static – Memory for the static variables are assigned only once in their life. Non-static variables are called instance variables void – is a NULL return type of Main method
  13. 13. 10/14/16 © Rays Technologies 13 Commands Console.write()/Console.WriteLine() command is used to write text at standard output device String is a data type Two strings are concated by + operator o “Hello” + name
  14. 14. 10/14/16 © Rays Technologies 14 Main method  The Main method is sometimes called the application's entry point.  Can be declared as  public static void Main(){}  OR  public static void Main(string args[]){}  OR public static int Main()  {… return errorCode}  OR  public static int Main(string args[])  {… return errorCode}
  15. 15. © Rays Technologies While 10/14/16 15
  16. 16. 10/14/16 © Rays Technologies 16 Print Hello C# 5 times - while  using System;  public class HelloWhile {  public static void Main(String[] args) { o boolean isAlive = true; o int round = 0; o while (isAlive) { o Console.WriteLine(“Basanti will dance"); o round++; o If(round>500 )  isAlive =false; o }  }}
  17. 17. © Rays Technologies For 10 Rs 5 shots How Much? Okey!! 10/14/16 17
  18. 18. © Rays Technologies For Loop using System; public class HelloFor { public static void Main() { ofor (int hits = 1; hits <= 5; hits++) { Console.WriteLine( “Shot Balloon"); o} o} } 10/14/16 18
  19. 19. 10/14/16 © Rays Technologies 19 Print Hello C# 5 times – do-while using System; public class HelloDoWhile { public static void Main() { o int i = 0; o do {  Console.WriteLine ( i+ “ Hello C#");  i++; o } while (i < 5); } }
  20. 20. 10/14/16 © Rays Technologies 20 Add.java using System; public class Add { public static void Main(String[] args) { oint a = 5; oint b = 10; oint sum = a + b; oConsole.WriteLine ("Sum is " + sum); } }
  21. 21. 10/14/16 © Rays Technologies 21 switch  public static void Main() {  String country = “India”;  switch(country) {  case “India” : o Console.WriteLine(“Language is Hindi"); o break;  case “US” :  case “England” : o Console.WriteLine(“Language is English”); o break;  default : o Console.WriteLine(“Don’t know language {0}”, country); o break;  }//switch  }//method
  22. 22. 10/14/16 © Rays Technologies 22 Value Types int long sbyte short float double 1 2 4 8 4 8 -128, +127 -9.223E18, +9.223E18 -32768, +32767 -2147483648, +2147483647 +3.4 E+38 +1.7 E+308 TypeType Size ByteSize Byte RangeRange char 2 0, 65535 (Unicode) bool 1 true, false 0 0 0 0 0 0 0 false DefaultDefault
  23. 23. 10/14/16 © Rays Technologies 23 Value Types uint ulong byte ushort decimal 1 2 4 8 16 0, 255 0 .. 264-1 0, 65535 0,4294967295 ± 1E-28 .. ±7.9E28 TypeType Size ByteSize Byte RangeRange 0 0 0 0 0 DefaultDefault
  24. 24. 10/14/16 © Rays Technologies 24 Other Data Types Reference types (composite) o objects o arrays strings is a reference data type
  25. 25. 10/14/16 © Rays Technologies 25 System.String class  public static void Main() {  String name = "Vijay Dinanth Chouhan";  Console.WriteLine(" String Length- " + name.Length);  Console.WriteLine(" 7 ths caharcter is- " + name[6]);  Console.WriteLine(" Dina index is- " + name.IndexOf("Dina"));  Console.WriteLine(" First i Position- " + name.IndexOf("i"));  Console.WriteLine(" Last i Position- " + name.LastIndexOf("i"));  Console.WriteLine(" a is replaced by b- " + name.Replace("a", "b"));  Console.WriteLine(" Chota vijay- " + name.ToLower());  Console.WriteLine(" Bada vijay- " + name.ToUpper());  Console.WriteLine(" Starts With Vijay- " + name.StartsWith("Vijay"));  Console.WriteLine(" Ends with han- " + name.EndsWith("han"));  Console.WriteLine(" Substring- " + name.Substring(6));  }
  26. 26. 10/14/16 © Rays Technologies 26 System.Math class  public static void main(String[] args) {  Console.WriteLine("Math functions");  Console.WriteLine(" Max 2,5 - " + Math.Max(2,5));  Console.WriteLine(" Min 2,5 - " + Math.Min(2,5));  Console.WriteLine(" Absolute 3.7 - " + Math.Abs(3.7));  Console.WriteLine(" Exp 10 - " + Math.Exp(10));  Console.WriteLine(" Square Root- " + Math.Sqrt(4));  }
  27. 27. 10/14/16 © Rays Technologies 27 Static vs Instance String name = “Vijay”; String surname = “Chohan” C.WL(name.Length); C.WL(surname.Length); String.Length C.WL(Math.Max(2,5)); C.WL(Math.Max(5,10));
  28. 28. 10/14/16 © Rays Technologies 28 Hello <Name> public class HelloName { public static void Main(String[] args) {  Console.WriteLine("Hello " + args[0]); } }
  29. 29. 10/14/16 © Rays Technologies 29 Hello Name – if <condition>  public class HelloName{  public static void Main(String[] args) { o if (args.Length == 1) {  Console.WriteLine("Hello " + args[0]); o } else {  Console.WriteLine("Usage : HelloName <name>"); o }  }  }
  30. 30. 10/14/16 © Rays Technologies 30 Hello All public class HelloAll { public static void Main(String[] args) { o for (int i = 0; i < args.Length; i++) {  Console.WriteLine(i + " = Hello " + args[i]); o } } }
  31. 31. 10/14/16 © Rays Technologies 31 Hello All - define Method  public static void Main(String[] args) { o PrintAll(args);  }// main  public static void PrintAll(String[] args) { o int size = args.Length; o for (int i = 0; i < size; i++) {  Console.WriteLine((i + 1) + " = Hello " + args[i]); o }  }//myMethod
  32. 32. 10/14/16 © Rays Technologies 32 Add.java public class Add { public static void Main(String[] args) { o int a = Integer32.Parse(args[0]); o int b = Integer32.Parse (args[1]); o int sum = a + b; o Console.WriteLine("Sum is " + sum); } }
  33. 33. 10/14/16 © Rays Technologies 33 Division public class Division { public static void Main(String[] args) { o int a = Integer32.Parse (args[0]); o int b = Integer32.Parse (args[1]); o double div = a/b; o Console.WriteLine("Division is " + div); } }
  34. 34. 10/14/16 © Rays Technologies 34 Return a Value public class Division3 { public static void Main(String[] args) { o int a = Integer.Parse (args[0]); o int b = Integer.Parse (args[1]); o double div = getDivision(a, b); o Console.WriteLine("Division is " + div); }  public static double getDivision(int a, int b) { o double div = a / b; o return div;  }  }
  35. 35. 10/14/16 © Rays Technologies 35 10 One Dimension Array 20 [0] 18 .. 10 8 6 4 2 [1] [8] [9] [2] [3] [4] [n] Length int[] table = new int[10]; int a = table[4]; int a = table[2]; int size = table.Length
  36. 36. 10/14/16 © Rays Technologies 36 10 Initialize an Array 20 [0] 18 .. 10 8 6 4 2 [1] [8] [9] [2] [3] [4] [n] Length int[] table = new int[10]; table[0] =2; table[1] =4; …. Or int[] table = {2,4,6,8,10,12,14,16,18, 20};
  37. 37. 10/14/16 © Rays Technologies 37 Other Data Type Arrays char[] chList = new char[5]; chList[0] = ‘A’…. Or char[] chList = {‘A’,’B’,’C’,’D’,’E’} String[] strList = new String[5]; strList[0] = “A” strList[1] = “Bee” Console.WriteLine(strList[0]); …. Or String[] strList = {“A”,”Bee”,”Cee”,”Dee”,”E”}
  38. 38. 10/14/16 © Rays Technologies 3810length 2D Array [0] 20 18 .. 10 8 6 4 2 [1] [8] [9] [2] [3] [4] [n] 30 27 .. 15 12 9 6 3 40 36 .. 20 16 12 8 4 90 81 .. 45 36 27 18 9 100 90 .. 50 40 30 20 10 … [0] [1] [2] [7] [8] 9 9 .. 9 9 9 9 9
  39. 39. 10/14/16 © Rays Technologies 39  int[][] table = new int[10][9];  table[1][5] = 5;  int size = table.Length;  int size = table[0].Length;  int[][] rows = new int[10][];  rows[0] = new int[9];  rows[1] = new int[19];  rows[2] = new int[29];  int xyz = new int[10][9][2];
  40. 40. 10/14/16 © Rays Technologies 40 Rectangular Array
  41. 41. 10/14/16 © Rays Technologies 41 3D Array 20 [0] 18 .. 10 8 6 4 2 [1] [8] [9] [2] [3] [4] [n] 30 27 .. 15 12 9 6 3 40 36 .. 20 16 12 8 4 90 81 .. 45 36 27 18 9 100 90 .. 50 40 30 20 10 [0] [1] [2] [8] [9] 20 18 .. 10 8 6 4 2 30 27 .. 15 12 9 6 3 40 36 .. 20 16 12 8 4 20 18 .. 10 8 6 4 30 27 .. 15 12 9 6 20 18 .. 10 8 6 4 2 30 27 .. 15 12 9 6 3 40 36 .. 20 16 12 8 4 90 81 .. 45 36 27 18 9 100 90 .. 50 40 30 20 10 90 81 .. 45 36 27 18 9 100 90 .. 50 40 30 20 10 … [0] [1] [2]
  42. 42. Disclaimer This is an educational presentation to enhance the skill of computer science students. This presentation is available for free to computer science students. Some internet images from different URLs are used in this presentation to simplify technical examples and correlate examples with the real world. We are grateful to owners of these URLs and pictures. © Rays Technologies 4210/14/16
  43. 43. Thank You! © Rays Technologies 43 www.SunilOS.com 10/14/16

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