1. 1/23/2016Assoc. Prof. Stoyan Bonev1 COS240 O-O Languages AUBG, COS dept Lecture 31 Title: C# Methods Reference: COS240 Syllabus

2. 1/23/2016Assoc. Prof. Stoyan Bonev2 Lecture Contents: Structure of a C# program –Accent on methods Components of a C# program –Methods –Types of parameters By value and by reference (out, ref) The params qualifier Named parameters Optional parameters Sample demo programs

3. Anatomy of a C# program

4. Java Programming: From Problem Analysis to Program Design, 3e 44Java Programming: From Problem Analysis to Program Design, 4e The Basics of a C# Program C# program: collection of classes. Classes capsulated as namespaces – named or unnamed Namespace: collection of related classes Class: collection of data items and methods Method: designed to accomplish a specific task There is a main method in every C# program. static void Main(string[] args) Main method provides the control of program flow.

5. C# Programming: From Problem Analysis to Program Design5 5 Main( ) Method “Entry point” for all applications –Where the program begins execution –Execution ends after last statement in Main( ) Can be placed anywhere inside the class definition Applications must have one Main( ) method Begins with uppercase character

6. C# Programming: From Problem Analysis to Program Design 6 6 C# Elements Figure 1-17 Relationship among C# elements

7. C# Programming: From Problem Analysis to Program Design7 7 Anatomy of a Method Methods defined inside classes Group program statements –Based on functionality –Called one or more times All programs consist of at least one method –Main( ) User-defined method

8. C# Programming: From Problem Analysis to Program Design8 8 /* SquareExample.csAuthor:Doyle*/ using System; namespace Square { public class SquareExample { public static void Main( ) { int aValue = 768; int result; result = aValue * aValue; Console.WriteLine(“{0} squared is {1}”, aValue, result); Console.Read( ); } Required method

9. C# Programming: From Problem Analysis to Program Design9 9 Anatomy of a Method ( continued ) Figure 3-1 Method components

10. C# Programming: From Problem Analysis to Program Design10C# Programming: From Problem Analysis to Program Design10 Modifiers Appear in method headings Appear in the declaration heading for classes and other class members Indicate how it can be accessed Types of modifiers –Static –Access

11. C# Programming: From Problem Analysis to Program Design11C# Programming: From Problem Analysis to Program Design11 Static Modifier Indicates member belongs to the type itself rather than to a specific object of a class Main( ) must include static in heading Members of the Math class are static –public static double Pow(double, double) Methods that use the static modifier are called class methods –Instance methods require an object

12. C# Programming: From Problem Analysis to Program Design12C# Programming: From Problem Analysis to Program Design12 Access Modifiers public protected internal protected internal private

13. C# Programming: From Problem Analysis to Program Design13C# Programming: From Problem Analysis to Program Design13 Level of Accessibility

14. C# Programming: From Problem Analysis to Program Design14C# Programming: From Problem Analysis to Program Design14 Return Type Indicates what type of value is returned when the method is completed Always listed immediately before method name void –No value being returned return statement –Required for all non-void methods –Compatible value

15. C# Programming: From Problem Analysis to Program Design15C# Programming: From Problem Analysis to Program Design15 Return Type ( continued ) public static double CalculateMilesPerGallon (int milesTraveled, double gallonsUsed) { return milesTraveled / gallonsUsed; } Compatible value (double) returned Return type

16. C# Programming: From Problem Analysis to Program Design16C# Programming: From Problem Analysis to Program Design16 Method Names Follow the rules for creating an identifier –Pascal case style –Action verb or prepositional phrase Examples –CalculateSalesTax( ) –AssignSectionNumber( ) –DisplayResults( ) –InputAge( ) –ConvertInputValue( )

17. C# Programming: From Problem Analysis to Program Design17C# Programming: From Problem Analysis to Program Design17 Parameters Supply unique data to method Appear inside parentheses –Include data type and an identifier In method body, reference values using identifier name –Parameter refers to items appearing in the heading –Argument for items appearing in the call Formal parameters Actual arguments

18. C# Programming: From Problem Analysis to Program Design18C# Programming: From Problem Analysis to Program Design18 Parameters ( continued ) public static double CalculateMilesPerGallon (int milesTraveled, double gallonsUsed) { return milesTraveled / gallonsUsed; } Call to method inside Main( ) method Console.WriteLine(“Miles per gallon = {0:N2}”, CalculateMilesPerGallon(289, 12.2)); Two formal parameters Actual arguments

19. C# Programming: From Problem Analysis to Program Design19C# Programming: From Problem Analysis to Program Design19 Parameters ( continued ) Like return types, parameters are optional –Keyword void not required (inside parentheses) – when there are no parameters public void DisplayMessage( ) { Console.Write(”This is “); Console.Write(”an example of a method ”); Console.WriteLine(“body. ”); return; // no value is returned }

20. C# Programming: From Problem Analysis to Program Design20C# Programming: From Problem Analysis to Program Design20 Method Body Enclosed in curly braces Include statements ending in semicolons –Declare variables –Do arithmetic –Call other methods Value-returning methods must include return statement

21. C# Programming: From Problem Analysis to Program Design21C# Programming: From Problem Analysis to Program Design21 Calling Class Methods Invoke a method Call to method that returns no value [qualifier].MethodName(argumentList); Qualifier –Square brackets indicate optional –Class or object name Call to method does not include data type Use IntelliSense

22. C# Programming: From Problem Analysis to Program Design22C# Programming: From Problem Analysis to Program Design22 Predefined Methods Extensive class library Console class –Overloaded methods –Write( ) –WriteLine( ) –Read( ) Not overloaded Returns an integer

23. C# Programming: From Problem Analysis to Program Design23C# Programming: From Problem Analysis to Program Design23 Call Read( ) Methods int aNumber; Console.Write(“Enter a single character: ”); aNumber = Console.Read( ); Console.WriteLine(“The value of the character entered: ” + aNumber); Enter a single character: a The value of the character entered: 97

24. C# Programming: From Problem Analysis to Program Design24C# Programming: From Problem Analysis to Program Design24 Call Read( ) Methods ( continued ) int aNumber; Console.WriteLine(“The value of the character entered: “ + (char) Console.Read( )); Enter a single character: a The value of the character entered: a

25. C# Programming: From Problem Analysis to Program Design25C# Programming: From Problem Analysis to Program Design25 Call ReadLine( ) Methods More versatile than the Read( ) Returns all characters up to the enter key Not overloaded Always returns a string String value must be parsed

26. C# Programming: From Problem Analysis to Program Design26 Call Parse( ) Predefined static method All numeric types have a Parse( ) method –double.Parse( " string number " ) –int.Parse( " string number " ) –char.Parse( " string number " ) –bool.Parse( " string number " ) Expects string argument –Argument must be a number – string format Returns the number (or char or bool)

27. C# Programming: From Problem Analysis to Program Design27 /* SquareInputValue.csAuthor: Doyle */ using System; namespace Square { class SquareInputValue { static void Main( ) { string inputStringValue; double aValue, result; Console.Write("Enter a value to be squared: "); inputStringValue = Console.ReadLine( ); aValue = double.Parse(inputStringValue); result = Math.Pow(aValue, 2); Console.WriteLine("{0} squared is {1} ", aValue, result); Console.ReadKey( ); } } } // Curly braces should be lined up

28. C# Programming: From Problem Analysis to Program Design28 Call Parse( ) ( continued ) string sValue = " true " ; Console.WriteLine (bool.Parse(sValue)); // displays True string strValue = " q " ; Console.WriteLine(char.Parse(strValue)); // displays q

29. C# Programming: From Problem Analysis to Program Design29 Call Parse( ) with Incompatible Value Console.WriteLine(char.Parse(sValue)); when sValue referenced “True” Figure 3-6 System.FormatException run-time error

30. TryParse() method The TryParse( ) method will convert a string value sent as an argument to its equivalent numeric value, but it doesn’t throw an exception when the conversion fails. Java Programming: From Problem Analysis to Program Design, 3e 30

31. TryParse( ) Method Parse( ) method and methods in Convert class convert string values sent as arguments to their equivalent numeric value –If the string value being converted is invalid, program crashes as an Exception is thrown. Two ways to avoid the program crash: Could test the value prior to doing conversion with an if statement Another option is to use the TryParse( ) method C# Programming: From Problem Analysis to Program Design31

32. TryParse( ) Method public static bool TryParse (string someStringValue, out int result) if (int.TryParse(inValue, out v1) = = false) Console.WriteLine("Did not input a valid integer - " + "0 stored in v1"); C# Programming: From Problem Analysis to Program Design32 String value returned from Console.ReadLine( ) Result stored here, when conversion occurs Test…if problem, prints message, does not try to convert

33. TryParse( ) Method Each of the built in data types have a TryParse( ) method –char.TryParse( ), int.TryParse( ), decimal.TryParse( ), etc If there is a problem with the data, 0 is stored in the out argument and TryParse( ) returns false. C# Programming: From Problem Analysis to Program Design33 Show LargestValue example

34. C# Programming: From Problem Analysis to Program Design34 Convert Class More than one way to convert from one base type to another –System namespace — Convert class — static methods –Convert.ToDouble( ) –Convert.ToDecimal( ) –Convert.ToInt32( ) –Convert.ToBoolean( ) –Convert.ToChar( ) int newValue = Convert.ToInt32(stringValue);

35. C# Programming: From Problem Analysis to Program Design35 Predefined methods C# Programming: From Problem Analysis to Program Design35

36. C# Programming: From Problem Analysis to Program Design36C# Programming: From Problem Analysis to Program Design36

37. C# Programming: From Problem Analysis to Program Design37C# Programming: From Problem Analysis to Program Design37

38. C# Programming: From Problem Analysis to Program Design38C# Programming: From Problem Analysis to Program Design38

39. C# Programming: From Problem Analysis to Program Design39C# Programming: From Problem Analysis to Program Design39 Math( ) Class double aValue = 78.926; double result1, result2; result1 = Math.Floor(aValue); // result1 = 78 result2 = Math.Sqrt(aValue); // result2 = 8.88403061678651 Console.Write(“aValue rounded to 2 decimal places” + “ is {0}”, Math.Round(aValue, 2)); aValue rounded to 2 decimal places is 78.93 Each call returns a value

40. C# Programming: From Problem Analysis to Program Design40C# Programming: From Problem Analysis to Program Design40 Method Calls That Return Values Line 1 int aValue = 200; Line 2 int bValue = 896; Line 3 int result; Line 4 result = Math.Max(aValue, bValue); // result = 896 Line 5 result += bValue * Line 6 Math.Max(aValue, bValue) – aValue; // result = 896 + (896 * 896 - 200) (result = 803512) Line 7 Console.WriteLine(“Largest value between {0} ” Line 8 + “and {1} is {2}”, aValue, bValue, Line 9 Math.Max(aValue, bValue)); In an assignment statement Part of arithmetic expression Argument to another method call

41. C# Programming: From Problem Analysis to Program Design41C# Programming: From Problem Analysis to Program Design41 Writing Your Own Class Methods [modifier(s)] returnType MethodName ( parameterList ) { // body of method - consisting of executable statements } void Methods –Simplest to write –No return statement

42. C# Programming: From Problem Analysis to Program Design42C# Programming: From Problem Analysis to Program Design42 Writing Your Own Class Methods – void Types public static void DisplayInstructions( ) { Console.WriteLine(“This program will determine how ” + “much carpet to purchase.”); Console.WriteLine( ); Console.WriteLine(“You will be asked to enter the ” + “ size of the room and ”); Console.WriteLine(“the price of the carpet, ” + ”in price per square yards.”); Console.WriteLine( ); } class method A call to this method looks like: DisplayInstructions( );

43. C# Programming: From Problem Analysis to Program Design43C# Programming: From Problem Analysis to Program Design43 Writing Your Own Class Methods – void Types ( continued ) public static void DisplayResults(double squareYards, double pricePerSquareYard) { Console.Write(“Total Square Yards needed: ”); Console.WriteLine(“{0:N2}”, squareYards); Console.Write(“Total Cost at {0:C} “, pricePerSquareYard); Console.WriteLine(“ per Square Yard: {0:C}”, (squareYards * pricePerSquareYard)); } static method called from within the class where it resides To invoke method – DisplayResults(16.5, 18.95);

44. C# Programming: From Problem Analysis to Program Design44C# Programming: From Problem Analysis to Program Design44 Value-Returning Method Has a return type other than void Must have a return statement –Compatible value Zero, one, or more data items may be passed as arguments Calls can be placed: –In assignment statements –In output statements –In arithmetic expressions –Or anywhere a value can be used

45. C# Programming: From Problem Analysis to Program Design45C# Programming: From Problem Analysis to Program Design45 Value-Returning Method ( continued ) public static double GetLength( ) { string inputValue; int feet, inches; Console.Write(“Enter the Length in feet: ”); inputValue = Console.ReadLine( ); feet =int.Parse(inputValue); Console.Write(“Enter the Length in inches: “); inputValue = Console.ReadLine( ); inches = int.Parse(inputValue); return (feet + (double) inches / 12); } Return type→ double double returned

46. C# Programming: From Problem Analysis to Program Design46C# Programming: From Problem Analysis to Program Design46 Types of Parameters C# offers both –Call by value parameters (default type) –Call by reference parameters

47. 1/23/2016Assoc. Prof. Stoyan Bonev47 Variables can hold either value types or reference types Value type - where a variable X contains a value type, it directly contains an entity with some value. No other variable Y can directly contain the object contained by X (although Y might contain an entity with the same value). Reference type - where a variable X contains a reference type, what it directly contains is something that refers to an object. Another variable Y can contain a reference to the same object referred to by X. Reference types actually hold the value of a memory address occupied by the object they reference.

48. 1/23/2016Assoc. Prof. Stoyan Bonev48

49. C# Programming: From Problem Analysis to Program Design49C# Programming: From Problem Analysis to Program Design49 Types of Parameters Call by value –Copy of the original value is made Other types of parameters –ref –out –params ref and out cause a method to refer to the same variable that was passed into the method. Useful when there is need to return more than one value

50. C# Programming: From Problem Analysis to Program Design50C# Programming: From Problem Analysis to Program Design50 Types of Parameters When you use ref/out, call by reference is assumed. You must include ref/out both in the call (actual argument) and in the method heading (formal parameter). They must match. The ref keyword cannot be used unless the original argument is initialized before it is sent to the method. This restriction does not exist for out.

51. C# Programming: From Problem Analysis to Program Design51C# Programming: From Problem Analysis to Program Design51 Types of Parameters Demo program Methods1.cs

52. C# Programming: From Problem Analysis to Program Design52C# Programming: From Problem Analysis to Program Design52 Types of Parameters Demo program parameters.cs

53. C# Programming: From Problem Analysis to Program Design53C# Programming: From Problem Analysis to Program Design53 Types of Parameters ( continued ) Figure 3-9 Call by reference versus value

54. C# Programming: From Problem Analysis to Program Design54 Types of Parameters Call by value –Copy of the original value is made Other types of parameters –ref –out –params ref and out cause a method to refer to the same variable that was passed into the method

55. Parameters Example // Code pulled from Parameters.cs solutions int testValue = 1; TestDefault(testValue); Console.WriteLine("Upon return from TestDefault " + "Value: {0}", testValue); Console.WriteLine( ); public static void TestDefault(int aValue) { aValue = 111; Console.WriteLine("In TestDefault - Value: {0}", aValue); } C# Programming: From Problem Analysis to Program Design55 Upon return from TestDefault Value: 1

56. Parameters Example ( continued ) // Code pulled from Parameters.cs solutions int testValue = 1; TestRef(ref testValue); Console.WriteLine("Upon return from TestRef " + "Value: {0}", testValue); Console.WriteLine( ); public static void TestRef (ref int aValue) { aValue = 333; Console.WriteLine("In TestRef - Value: {0}", aValue); } C# Programming: From Problem Analysis to Program Design56 Upon return from TestRef Value: 333

57. Parameters Example ( continued ) // Code pulled from Parameters.cs solutions int testValue2; TestOut(out testValue2); Console.WriteLine("Upon return from TestOut " + "Value: {0}", testValue2); Console.WriteLine( ); public static void TestOut (out int aValue) { aValue = 222; Console.WriteLine("In TestOut - Value: {0}", aValue); } C# Programming: From Problem Analysis to Program Design57 Upon return from TestOut Value: 222

58. Parameters.cs C# Programming: From Problem Analysis to Program Design58 Figure 3-8 Output from ParameterClass example

59. C# Programming: From Problem Analysis to Program Design59 Types of Parameters ( continued ) Figure 3-9 Call by reference versus value

60. Testing Parameters App C# Programming: From Problem Analysis to Program Design60 Figure 3-10 Visual Studio comment out icon Comment/uncomment sections while testing

61. Demo Programs and Exercises Java Programming: From Problem Analysis to Program Design, 3e 61

62. Demo Programs and Exercises Write a method with two integer parameters and no return value which swaps/exchanges/ the values of its parameters. Test the method with value parameters Test the method with ref parameters Test the method with out parameters Java Programming: From Problem Analysis to Program Design, 3e 62

63. Demo Programs // PP parameter passing mechanisms - swap by value public static void swapByVal(int pa, int pb) { int temp; temp = pa; pa = pb; pb = temp; } //=================================== // Test PP parameter passing mechanisms by value int a, b; a = 20; b = 50; Console.WriteLine("Before swapByVal a={0}, b={1}", a, b); swapByVal(a, b); Console.WriteLine(" After swapByVal a={0}, b={1}", a, b); Java Programming: From Problem Analysis to Program Design, 3e 63

64. Demo Programs // PP parameter passing mechanisms - swap by ref public static void swapByRef1(ref int pa, ref int pb) { int temp; temp = pa; pa = pb; pb = temp; } //============================================ // Test PP parameter passing mechanisms by ref int a, b; a = 70; b = 90; Console.WriteLine("Before swapByRef1 a={0}, b={1}", a, b); swapByRef1(ref a, ref b); Console.WriteLine(" After swapByRef1 a={0}, b={1}", a, b); Java Programming: From Problem Analysis to Program Design, 3e 64

65. Demo Programs // PP parameter passing mechanisms - swap by out public static void swapByRef2(out int pa, out int pb) { pa = 230; pb = 250; } //================================ // Test PP parameter passing mechanisms by out int c, d; // both vars not initialized Console.WriteLine("Before swapByRef2 c={0}, d={1}", c, d); swapByRef2(out c, out d); Console.WriteLine(" After swapByRef2 c={0}, d={1}", c, d); Java Programming: From Problem Analysis to Program Design, 3e 65

66. C# Programming: From Problem Analysis to Program Design66C# Programming: From Problem Analysis to Program Design66 Params Parameter Keyword params used –Appears in formal parameter list (heading to the method) –Must be last parameter listed in the method heading Indicates number of arguments to the method that may vary

67. C# Programming: From Problem Analysis to Program Design67 Params Parameters When a method uses the params modifier, the parameter is considered a parameter array. It is used to indicate that the number of arguments to the method may vary. The params argument appears in method heading only. It is prefix of a formal parameter – array identifier and must be the last parameter listed. That formal parameter cannot be defined as ref or as out parameter. Demo program VaryingArguments.cs C# Programming: From Problem Analysis to Program Design67

68. C# Programming: From Problem Analysis to Program Design68C# Programming: From Problem Analysis to Program Design68 Types of Parameters Demo program VaryingArguments.cs

69. C# Programming: From Problem Analysis to Program Design69 Params Parameters using System; namespace VaryingArguments { class VaryingArguments { public static void Main() { DisplayItems(1, 2, 3, 5); int[] anArray = new int[5] {100, 200, 300, 400, 500}; DisplayItems(anArray); DisplayItems(1500, anArray[1] * anArray [2]); } public static void DisplayItems(params int[] item) { for ( int i = 0 ; i < item.Length ; i++ ) { Console.Write(item[i] + "\t"); } Console.WriteLine(); } } // end of class } // end of namespace C# Programming: From Problem Analysis to Program Design69

70. C# Programming: From Problem Analysis to Program Design70 Params Parameters Demo program VaryingArguments.cs A method may be called with a single value. Another call to the same method may send 4, or 10, or 100 values, or an array of values A variable number of arguments are accepted when params argument is included. Makes method very flexible. C# Programming: From Problem Analysis to Program Design70

71. Demo Programs Evolution of the routine concept applied to C# methods 71

72. Method Evolution Overloaded methods Java Programming: From Problem Analysis to Program Design, 3e 72

73. Method Evolution public static void displaystr() { for(int i=1; i<=1; i++) { Console.WriteLine("Bulgaria"); } Console.WriteLine("\n"); } Java Programming: From Problem Analysis to Program Design, 3e 73

74. Method Evolution public static void displaystr(int pn) { for(int i=1; i<=pn; i++) { Console.WriteLine("Bulgaria"); } Console.WriteLine("\n"); } Java Programming: From Problem Analysis to Program Design, 3e 74

75. Method Evolution public static void displaystr(String ps) { for(int i=1; i<=1; i++) { Console.WriteLine(ps); } Console.WriteLine("\n"); } Java Programming: From Problem Analysis to Program Design, 3e 75

76. Method Evolution public static void displaystr(String ps, int pn) { for(int i=1; i<=pn; i++) { Console.WriteLine(ps); } Console.WriteLine("\n"); } Java Programming: From Problem Analysis to Program Design, 3e 76

77. Method Evolution public static void displaystr() { for(int i=1; i<=1; i++) { Console.WriteLine("Bulgaria"); } } //======================================================== public static void displaystr(String ps) { for(int i=1; i<=1; i++) { Console.WriteLine(ps); } } //======================================================== public static void displaystr(int pn) { for(int i=1; i<=pn; i++) { Console.WriteLine("Bulgaria"); } } //======================================================== public static void displaystr(String ps, int pn) { for(int i=1; i<=pn; i++) { Console.WriteLine(ps); } } Java Programming: From Problem Analysis to Program Design, 3e 77

78. Method Evolution Overloaded methods // Test PP overloaded methods displaystr(); displaystr("Germany"); displaystr(2); displaystr("United Kingdom", 4); Java Programming: From Problem Analysis to Program Design, 3e 78

79. Method Evolution Default arguments methods Java Programming: From Problem Analysis to Program Design, 3e 79

80. Method Evolution Default arguments methods // // PP default arguments methods public static double aveVal(int pa=10, int pb=20, int pc=30, int pd=40) { return ( pa + pb + pc + pd ) / 4.0; } Java Programming: From Problem Analysis to Program Design, 3e 80

81. Method Evolution Default arguments methods // // Test PP default arguments functions Console.WriteLine("\n {0}", aveVal()); Console.WriteLine("\n {0}", aveVal(100)); Console.WriteLine("\n {0}", aveVal(100, 200)); Console.WriteLine("\n {0}", aveVal(100, 200, 300)); Console.WriteLine("\n {0}", aveVal(100, 200, 300, 400)); Java Programming: From Problem Analysis to Program Design, 3e 81

82. Optional Parameters May assign default values to parameters –When you assign a default value to a parameter, it then becomes an optional parameter public static void DoSomething(string name, int age = 21, bool currentStudent = true, string major = "CS") Can now call DoSomething( ) and send in arguments for the default value or the default values will be assigned to the parameters C# Programming: From Problem Analysis to Program Design82

83. Method Evolution Named parameters Java Programming: From Problem Analysis to Program Design, 3e 83

84. Named Parameters Named arguments free you from the need to remember or to look up the order of parameters for the method call DoSomething (name: “Robert Wiser", age: 20); DoSomething (name: "Paul Nelson", major: “IS"); DoSomething (name: “Fred Terrell", age: 25, major: “BUS"); C# Programming: From Problem Analysis to Program Design84

85. Method Evolution An artefact with C# methods Java Programming: From Problem Analysis to Program Design, 3e 85

86. Method Evolution An artefact with C# methods Given a method int add(int pa, int pb) { return pa + pb; } Java Programming: From Problem Analysis to Program Design, 3e 86

87. Method Evolution An artefact with C# methods Are the call statements valid? int a = 20, b = 50; int x = add(5, 6); int y = add(a, b);; Int z = add(a + 5 * 6, b – 7 * 8); Int t = add(a = 5 * 6, b = 7 * 8); Java Programming: From Problem Analysis to Program Design, 3e 87

88. C# Programming: From Problem Analysis to Program Design88 Practical session Expand the program Methods1.cs adding more methods that reside in the same class with method Main(): Iterative GCD – gcdi() Iterative/Recursive factorial – facti(), factr() Iterative/Recursive Fibonacci – fiboi(), fibor() Iterative/Recursive Sum(1..n) – sumi(), sumr() Iterative/Recursive Power operator simulator – powi(), powr() C# Programming: From Problem Analysis to Program Design88

89. C# Programming: From Problem Analysis to Program Design89 Practical session Expand the program Parameters.cs adding more methods that reside in the same class with method Main(): Method void swap(int pa, int pb) that exchanges the values of its parameters/arguments Test the swap method with: –Input parameters by value –Output ref parameters –Output out parameters C# Programming: From Problem Analysis to Program Design89

90. Thank You for Your attention!