IST311 Chapter 8: C# Collections - Index-Sequential Search List & Dictionary PROGRAM

Transcription

1 IST311 Chapter 8: C# Collections - Index-Sequential Search List & Dictionary PROGRAM class Program static void Main(string[] args) //create a few employees Employee e1 = new Employee( , "Tiryon", "Lannister", ); Employee e2 = new Employee( , "John", "Snow", 1); Employee e3 = new Employee( , "Daenerys", "Targeryan", ); Employee e4 = new Employee( , "Arya", "Stark", 10000); //make an index based on employee's ID numbers Dictionary<int, Employee> indexonid = new Dictionary<int, Employee>(); indexonid.add( , e1); indexonid.add( , e2); indexonid.add( , e3); indexonid.add( , e4); //Locate employee by ID (do it quickly using index) Employee e = indexonid[ ]; Console.WriteLine( e ); //create a second index on employee's FIRSTNAME Dictionary<string, Employee> indexonfirstname = new Dictionary<string, Employee>(); indexonfirstname.add("tiryon", e1); indexonfirstname.add("john", e2); indexonfirstname.add("daenerys", e3); indexonfirstname.add("arya", e4); //find employee using FirstName index (very quick!) e = indexonfirstname["john"]; Console.WriteLine( "FIRST TIME " + e ); // //CAUTION: collisions may occur when key value is duplicated //Employee e5 = new Employee( , "John", "Troubles", 2000); //indexonfirstname.add("john", e5); //doesn't work - key already in dictionary //e = indexonfirstname["john"]; //Console.WriteLine("SECOND TIME " + e); //TODO: need to learn how to // (1) deal with duplicate key values in dictionary (perhaps Dictionary<K, List<V>>) // (2) search for a key not present in the dictionary // (3) try-catch exception mechanism //e = indexonid[ ]; //Console.WriteLine( e ); //ex. this doesn't work - key not in dictionary List<Employee> people = new List<Employee>(); people.add(e1); people.add(e2); people.add(e3);

2 people.add(e4); people.add(new Employee( , "Sansa", "Stark", )); //find employee using sequential search (easy-slow-inefficient) e = FindEmployeeUsingIdSequentialSearch(people, ); if ( e == null) Console.WriteLine( "Sorry - no data found "); else Console.WriteLine( e ); //create a department, add some employees to it Department d1 = new Department(101, "Marketing"); Console.WriteLine( d1 ); d1.addemployee(e1); d1.addemployee(e3); d1.addemployee(e1); Console.WriteLine( d1 ); private static Employee FindEmployeeUsingIdSequentialSearch(List<Employee> people, int idvalue) foreach(employee e in people) if (e.empid == idvalue) return e; return null; CLASS DIAGRAM

3 EMPLOYEE class Employee private int empid; public int EmpId get return empid; set empid = value; private string firstname; public string FirstName get return firstname; set firstname = value; private string lastname; public string LastName get return lastname; set lastname = value; private double salary; public double Salary get return salary; set salary = value; //constructor(s) public Employee() EmpId = 0; FirstName = "n.a."; LastName = "n.a."; Salary = 0; public Employee( int empidvalue, string firstnamevalue, string lastnamevalue, double salaryvalue) EmpId = empidvalue; FirstName = firstnamevalue; LastName = lastnamevalue; Salary = salaryvalue; //user-defined methods override public string ToString()

4 string result = "Employee ["; result += " ID=" + EmpId; result += " First=" + FirstName; result += " Last=" + LastName; result += " Salary=" + Salary; result += " HashCode=" + this.gethashcode(); result += " ]"; return result; DEPARTMENT class Department private int dno; public int Dno get return dno; set dno = value; private string depname; public string DepName get return depname; set depname = value; private List<Employee> people; public List<Employee> People get return people; set people = value; //CONSTRUCTORS public Department(int dnovalue, string dnamevalue) Dno = dnovalue; DepName = dnamevalue; people = new List<Employee>(); //USER-DEFINED METHODS override public string ToString() string result = " Departmen ["; result += " Dno= " + Dno; result += ",DeptName= " + DepName; result += " PEOPLE[ "; foreach(employee e in people)

5 result += "\n\t" + e; result += " ] ]"; return result; public void AddEmployee(Employee e) people.add(e); internal Employee workers get throw new System.NotImplementedException(); set CONSOLE