ArrayList and your own object: Use the BinarySearch() method to search myArrayList for an object : ArrayList object « Data Structure « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Data Structure
3. ArrayList object

using System;
using System.Collections;

class Employee : IComparable
{
  public string Name;
  public int Number;

  public Employee(string Name, int Number)
  {
    this.Name = Name;
    this.Number = Number;
  }

  public override string ToString()
  {
    return "Name is " + Name + ", Number is " + Number;
  }

  public int Compare(object lhs, object rhs)
  {
    Employee lhsEmployee = (Employee) lhs;
    Employee rhsEmployee = (Employee) rhs;
    if (lhsEmployee.Number < rhsEmployee.Number) {
      return -1;
    } else if (lhsEmployee.Number > rhsEmployee.Number) {
      return 1;
    } else {
      return 0;
    }
  }

  public int CompareTo(object rhs) {
    return Compare(this, rhs);
  }
}

class MainClass
{
  public static void DisplayArrayList(string arrayListName, ArrayList myArrayList) {
    for (int i = 0; i < myArrayList.Count; i++) {
      Console.WriteLine(arrayListName + "[" + i + "] = " + myArrayList[i]);
    }
  }

  public static void Main()
  {
    ArrayList myArrayList = new ArrayList();

    // add four Employee objects to myArrayList using the Add() method
    Console.WriteLine("Adding four Employee objects to myArrayList");
    Employee myM = new Employee("M", 2001);
    Employee myB = new Employee("B", 2001);
    Employee myC = new Employee("C", 1999);
    Employee myT = new Employee("T", 1979);
    myArrayList.Add(myM);
    myArrayList.Add(myB);
    myArrayList.Add(myC);
    myArrayList.Add(myT);
    DisplayArrayList("myArrayList", myArrayList);

    myArrayList.Sort();
    DisplayArrayList("myArrayList", myArrayList);

    int index2 = myArrayList.BinarySearch(myC);
    Console.WriteLine("Found myC at index " + index2);

  }
}

Adding four Employee objects to myArrayList
myArrayList[0] = Name is M, Number is 2001
myArrayList[1] = Name is B, Number is 2001
myArrayList[2] = Name is C, Number is 1999
myArrayList[3] = Name is T, Number is 1979
myArrayList[0] = Name is T, Number is 1979
myArrayList[1] = Name is C, Number is 1999
myArrayList[2] = Name is M, Number is 2001
myArrayList[3] = Name is B, Number is 2001
Found myC at index 1