Enumerators and Foreach : Enum « Data Types « C# / C Sharp

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2. Data Types
3. Enum

Enumerators and Foreach

   
/*
A Programmer's Introduction to C# (Second Edition)
by Eric Gunnerson

Publisher: Apress  L.P.
ISBN: 1-893115-62-3
*/
// 19 - Indexers and Enumerators\Enumerators and Foreach
// copyright 2000 Eric Gunnerson
using System;
using System.Collections;

// Note: This class is not thread-safe
class IntList: IEnumerable
{
    int[] values = new int[10];
    int allocated = 10;
    int count = 0;
    int revision = 0;
    
    public void Add(int value)
    {
        // reallocate if necessary
        if (count + 1 == allocated)
        {
            int[] newValues = new int[allocated * 2];
            for (int index = 0; index < count; index++)
            {
                newValues[index] = values[index];
            }
            allocated *= 2;
        }        
        values[count] = value;
        count++;
        revision++;
    }
    
    public int Count
    {
        get
        {
            return(count);
        }
    }
    
    void CheckIndex(int index)
    {
        if (index >= count)
        throw new ArgumentOutOfRangeException("Index value out of range");
    }
    
    public int this[int index]
    {
        get
        {
            CheckIndex(index);
            return(values[index]);
        }
        set
        {
            CheckIndex(index);
            values[index] = value;
            revision++;
        }
    }
    
    public IEnumerator GetEnumerator()
    {
        return(new IntListEnumerator(this));
    }
    
    internal int Revision
    {
        get
        {
            return(revision);
        }
    }
}

class IntListEnumerator: IEnumerator
{
    IntList    intList;
    int revision;
    int index;
    
    internal IntListEnumerator(IntList intList)
    {
        this.intList = intList;
        Reset();
    }
    
    public bool MoveNext()
    {
        index++;
        if (index >= intList.Count)
        return(false);
        else
        return(true);
    }
    
    public object Current
    {
        get
        {
            if (revision != intList.Revision)
            throw new InvalidOperationException("Collection modified while enumerating.");
            return(intList[index]);
        }
    }
    
    public void Reset()
    {
        index = -1;
        revision = intList.Revision;
    }
}

public class EnumeratorsandForeach {
    public static void Main()
    {
        IntList list = new IntList();
        
        list.Add(1);
        list.Add(55);
        list.Add(43);
        
        foreach (int value in list)
        {
            Console.WriteLine("Value = {0}", value);
        }
        
        foreach (int value in list)
        {
            Console.WriteLine("Value = {0}", value);
            list.Add(124);
        }
    }
}

           
         
    
    
  

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2.	Enumerations Initialization 2
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4.	Enum declare and use it
5.	Demonstrate an enumeration
6.	Enum by IEnumerable
7.	Enum Values
8.	The use of an enumeration that defines the positions of the planets in the solar system relative to the Sun
9.	Illustrates the use of an enumeration that defines the orbital periods of the first four planets in days
10.	Illustrates the use of an enumeration that defines the orbital periods of the first four planets in days, using a base type of long
11.	how a derived class may override an existing enumeration in a base class
12.	A public enum in one class from another class
13.	Demonstrate an enumerator
14.	Demonstrate IDictionaryEnumerator
15.	Enumerations:Bit Flag Enums 1
16.	Enumerations:Bit Flag Enums 2
17.	Enumerations:The System.Enum Type
18.	Enumerations: The System.Enum Type 2
19.	Enum data type comparison
20.	Enum.IsDefined()
21.	Get all stats for EmpType.
22.	Enum Parse
23.	Get Enum's type, hex and value.
24.	Enum.Format()
25.	Get underlying type
26.	switch statement with Enum and call its ToString function
27.	Format enum value
28.	Wrap an enumerable so that clients can't get to the underlying implementation via a down-case
29.	Try to parse Enum
30.	Enum To Array
31.	Get Enum Description
32.	Convert all Enum value to a List
33.	Get all values from an Enum type
34.	Get Enum Values
35.	Fill all enum value to a List
36.	Retrieves the enum field associated with the specified value. A return value indicates whether the conversion succeeded.
37.	Provides a description for an enumerated type.
38.	Get Description