Methods

1. SWE 344 Internet Protocols & Client Server Programming Methods

2. Method Structure • Methods are extremely useful because they allow you to separate your logic into different units. • You can pass information to methods, have it perform one or more statements, and retrieve a return value. • The capability to pass parameters and return values is optional and depends on what you want the method to do. • The syntax required for creating a method: • attributes modifiers return-type method-name(parameters ) • { • statements • }

3. Example #1: Method Structure using System; classOneMethod { publicstaticvoid Main() { stringmyChoice; OneMethodom = newOneMethod(); do { myChoice = om.getChoice(); // Make a decision based on the user's choice switch (myChoice) { case"A": case"a": Console.WriteLine("You wish to add an address."); break; case"D": case"d": Console.WriteLine("You wish to delete an address."); break; case"M": case"m": Console.WriteLine("You wish to modify an address."); break;

4. Example #1: Method Structure • case"V": • case"v": • Console.WriteLine("You wish to view the address list."); • break; • case"Q": • case"q": • Console.WriteLine("Bye."); • break; • default: • Console.WriteLine("{0} is not a valid choice",myChoice); • break; • } • // Pause to allow the user to see the results • Console.WriteLine(); • Console.Write("press Enter key to continue..."); • Console.ReadLine(); • Console.WriteLine(); • } while (myChoice != "Q" || myChoice != "q"); // Keep going until the user wants to quit • }

5. Example #1: Method Structure • stringgetChoice() • { • stringmyChoice; • // Print A Menu • Console.WriteLine("My Address Book\n"); • Console.WriteLine("A - Add New Address"); • Console.WriteLine("D - Delete Address"); • Console.WriteLine("M - Modify Address"); • Console.WriteLine("V - View Addresses"); • Console.WriteLine("Q - Quit\n"); • Console.Write("Choice (A,D,M,V,or Q): "); • // Retrieve the user's choice • myChoice = Console.ReadLine(); • Console.WriteLine(); • returnmyChoice; • } • }

6. Example #2: Method Structure using System; classAddress { publicstring name; publicstring address; } classMethodParams { publicstaticvoid Main() { stringmyChoice; MethodParams mp = newMethodParams(); do { // show menu and get input from user myChoice = mp.getChoice(); // Make a decision based on the user's choice mp.makeDecision(myChoice); // Pause to allow the user to see the results Console.Write("press Enter key to continue..."); Console.ReadLine(); Console.WriteLine(); } while (myChoice != "Q"||myChoice != "q"); // Keep going until the // user wants to quit }

7. Example #2: Method Structure • // show menu and get user's choice • stringgetChoice() • { • stringmyChoice; • // Print A Menu • Console.WriteLine("My Address Book\n"); • Console.WriteLine("A - Add New Address"); • Console.WriteLine("D - Delete Address"); • Console.WriteLine("M - Modify Address"); • Console.WriteLine("V - View Addresses"); • Console.WriteLine("Q - Quit\n"); • Console.WriteLine("Choice (A,D,M,V,or Q): "); • // Retrieve the user's choice • myChoice = Console.ReadLine(); • returnmyChoice; • } • // make decision • voidmakeDecision(stringmyChoice) • { • Addressaddr = newAddress(); • switch (myChoice) • { • case"A": • case"a": • addr.name = "Joe"; • addr.address = “Hail"; • this.addAddress(refaddr); • break;

8. Example #2: Method Structure • case"D": • case"d": • addr.name = "Robert"; • this.deleteAddress(addr.name); • break; • case"M": • case"m": • addr.name = "Matt"; • this.modifyAddress(outaddr); • Console.WriteLine("Name is now {0}.", addr.name); • break; • case"V": • case"v": • this.viewAddresses("Cheryl", "Joe", "Matt", "Robert"); • break; • case"Q": • case"q": • Console.WriteLine("Bye."); • break; • default: • Console.WriteLine("{0} is not a valid choice", myChoice); • break; • } • }

9. Example #2: Method Structure • // insert an address • voidaddAddress(refAddressaddr) • { • Console.WriteLine("Name: {0}, Address: {1} added.", addr.name, addr.address); • } • // remove an address • voiddeleteAddress(string name) • { • Console.WriteLine("You wish to delete {0}'s address.", name); • } • // change an address • voidmodifyAddress(outAddressaddr) • { • //Console.WriteLine("Name: {0}.", addr.name); // causes error! • addr = newAddress(); • addr.name = "Joe"; • addr.address = “Hail"; • } • // show addresses • voidviewAddresses(paramsstring[] names) • { • foreach (string name in names) • { • Console.WriteLine("Name: {0}", name); • } • } • }

10. ref tells the compiler that the object is initialized before entering the function, while out tells the compiler that the object will be initialized inside the function.

11. Question 2: Find the sum and multiplication of two numbers .Read the numbers from the user. Write the methods for sum and multiplication and return the value. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace lab3 { class Class1 { public static void Main() { int x, y,sum,mult; Console.Write("Enter first number:"); x = Convert.ToInt16(Console.ReadLine()); Console.Write("Enter second number:");

12. y = Convert.ToInt16(Console.ReadLine()); math m1 = new math(); sum = m1.sum(x, y); mult = m1.mult(x, y); Console.WriteLine("Sum={0}", sum); Console.WriteLine("Multiplication={0}", mult); Console.ReadLine(); } } class math { public int sum(int a, int b) { return a + b; } public intmult(int a, int b) { return a * b; } }}

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