Methods SWE 344 Internet Protocols & Client Server Programming

 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 } Method Structure 2

using System; class OneMethod { public static void Main() { string myChoice; OneMethod om = new OneMethod(); 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; Example #1: Method Structure 3

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 } Example #1: Method Structure 4

string getChoice() { string myChoice; // 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(); return myChoice; } Example #1: Method Structure 5

using System; class Address { public string name; public string address; } class MethodParams { public static void Main() { string myChoice; MethodParams mp = new MethodParams(); 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 } Example #2: Method Structure 6

// show menu and get user's choice string getChoice() { string myChoice; // 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(); return myChoice; } // make decision void makeDecision(string myChoice) { Address addr = new Address(); switch (myChoice) { case "A": case "a": addr.name = "Joe"; addr.address = “Hail"; this.addAddress(ref addr); break; Example #2: Method Structure 7

case "D": case "d": addr.name = "Robert"; this.deleteAddress(addr.name); break; case "M": case "m": addr.name = "Matt"; this.modifyAddress(out addr); 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; } Example #2: Method Structure 8

// insert an address void addAddress(ref Address addr) { Console.WriteLine("Name: {0}, Address: {1} added.", addr.name, addr.address); } // remove an address void deleteAddress(string name) { Console.WriteLine("You wish to delete {0}'s address.", name); } // change an address void modifyAddress(out Address addr) { //Console.WriteLine("Name: {0}.", addr.name); // causes error! addr = new Address(); addr.name = "Joe"; addr.address = “Hail"; } // show addresses void viewAddresses(params string[] names) { foreach (string name in names) { Console.WriteLine("Name: {0}", name); } Example #2: Method Structure 9

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 int mult(int a, int b) { return a * b; } }}

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