Maha

Maha

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NP87 foreach

Mar 17 2008 7:47 AM

Hi Guys

 

NP87 foreach

 

foreach is used when checks size of the array. In this program it is used without array. Anyone knows please explain the reason.

    

Cars carLot = new Cars();

 

foreach (Car c in carLot)

{

 …………………          

}

 

Thank you

 

 

using System;

using System.Collections;

 

namespace ObjEnum

{

   public class Car

   {

      // Internal state data.

      private int currSpeed;

      private int maxSpeed;

      private string petName;

 

      // Is the car alive or dead?

      bool carIsDead;

 

      // A car has-a radio.

      private Radio theMusicBox = new Radio();

 

      public Car()

      {

         maxSpeed = 100;

      }

 

      public Car(string name, int max, int curr)

      {

         currSpeed = curr;

         maxSpeed = max;

         petName = name;

      }

 

      public void CrankTunes(bool state)

      {

         // Tell the radio play (or not).

         // Delegate request to inner object.

         theMusicBox.TurnOn(state);

      }

 

      public void SpeedUp(int delta)

      {

         // If the car is dead, just say so...

         if (carIsDead)

         {

            Console.WriteLine("{0} is out of order....", petName);

         }

         else     // Not dead, speed up.

         {

            currSpeed += delta;

            if (currSpeed >= maxSpeed)

            {

               Console.WriteLine("{0} has overheated...", petName);

               carIsDead = true;

            }

            else

               Console.WriteLine("\tCurrSpeed = {0}", currSpeed);

         }

      }

 

      // Properties.

      public string PetName

      {

         get { return petName; }

         set { petName = value; }

      }

      public int CurrSpeed

      {

         get { return currSpeed; }

         set { currSpeed = value; }

      }

      public int MaxSpeed

      {

         get { return maxSpeed; }

         set { maxSpeed = value; }

      }

   }

 

   // No pun intended!

   public class CarDriver

   {

      public static void Main()

      {

         Cars carLot = new Cars();

 

         Console.WriteLine("***** Here are the cars in your lot *****");

         foreach (Car c in carLot)

         {

            Console.WriteLine("-> Name: {0}", c.PetName);

            Console.WriteLine("-> Max speed: {0}", c.MaxSpeed);

            Console.WriteLine();

         }

 

         #region Working with raw IEnumerator

         /*

                  // Now ala IEnumerator

                  IEnumerator itfEnum;

                  itfEnum = (IEnumerator)carLot;

 

                  // Reset the cursor to the beginning.

                  itfEnum.Reset();

 

                  // Advance internal cursor by 1.

                  itfEnum.MoveNext();

           

                  // Cast to a Car and crank some tunes.

                  object curCar = itfEnum.Current;

                  ((Car)curCar).CrankTunes(true);

                  */

         #endregion

      }

   }

 

   public class Cars : IEnumerable // , IEnumerator

   {

      // This class maintains an array of cars.

      private Car[] carArray;

 

      // Current position in array.

      // int pos = -1;

 

      public Cars()

      {

         carArray = new Car[4];

         carArray[0] = new Car("FeeFee", 200, 0);

         carArray[1] = new Car("Clunker", 90, 0);

         carArray[2] = new Car("Zippy", 30, 0);

         carArray[3] = new Car("Fred", 30, 0);

      }

 

      #region Raw IEnumerator impl

      /*

            // Implementation of IEnumerator.

            public bool MoveNext()

            {

                  if(pos < carArray.Length)

                  {

                        pos++;

                        return true;

                  }

                  else

                        return false;

            }

            public void Reset()

            {

                  pos = 0;

            }

            public object Current

            {

                  get { return carArray[pos]; }

            }

            */

      #endregion

 

      // This must be present in order to let the foreach

      // expression to iterate over our array.

      // IEnumerable implemtation.

      public IEnumerator GetEnumerator()

      {

         // return (IEnumerator)this;

 

         // Now just get back the IEnumerator from

         // the internal array!

         return carArray.GetEnumerator();

      }

   }

 

   public class Radio

   {

      public void TurnOn(bool on)

      {

         if (on)

            Console.WriteLine("Jamming...");

         else

            Console.WriteLine("Quiet time...");

      }

   }

}

/*

***** Here are the cars in your lot *****

-> Name: FeeFee

-> Max speed: 200

 

-> Name: Clunker

-> Max speed: 90

 

-> Name: Zippy

-> Max speed: 30

 

-> Name: Fred

-> Max speed: 30

*/

 

 


Answers (12)