C# | Getting a subset of the elements from the source ArrayList

ArrayList.GetRange(Int32, Int32) Method is used to get an ArrayList which will represent a subset of the elements in the source ArrayList.

Syntax:

public virtual System.Collections.ArrayList GetRange (int index, int count);

Parameters:

index: It is of Int32 type and represents the zero-based ArrayList index at which the range starts.
count: It is of Int32 type and represents the number of elements in the range.

Return Value: This method returns an ArrayList which represents a subset of the elements in the source ArrayList.

Exceptions:

ArgumentOutOfRangeException: If the value of the index is less than zero, or if the value of count is less than zero.
ArgumentException: If the value of an index and count does not denote a valid range of elements in the ArrayList.

Below programs illustrate the above-discussed method:

Example 1:

// C# program to illustrate the 
// concept of GetRange() Method 
using System; 
using System.Collections; 
  
class GFG { 
  
    // Main method 
    public static void Main() 
    { 
  
        // Creates and initializes 
        // a new ArrayList. 
        ArrayList myarraylist = new ArrayList(); 
        myarraylist.Add("Welcome"); 
        myarraylist.Add("to"); 
        myarraylist.Add("Geeks"); 
        myarraylist.Add("for"); 
        myarraylist.Add("Geeks"); 
        myarraylist.Add("portal"); 
  
        // Creates and initializes queue 
        Queue mynewList = new Queue(); 
        mynewList.Enqueue("This"); 
        mynewList.Enqueue("is"); 
        mynewList.Enqueue("C#"); 
        mynewList.Enqueue("tutorial"); 
  
        // Displays the values of six  
        // elements starting at index 0. 
        ArrayList newarraylist = myarraylist.GetRange(0, 6); 
        Console.WriteLine("Elements are:"); 
        Displaydata(newarraylist, '\n'); 
  
        // Replaces the values of six elements  
        // starting at index 1 with the values 
        // in the queue. 
        myarraylist.SetRange(2, mynewList); 
  
        // Displays the values of six  
        // elements starting at index 0. 
        newarraylist = myarraylist.GetRange(0, 6); 
        Console.WriteLine("\nNow elements are:"); 
        Displaydata(newarraylist, '\n'); 
    } 
  
    public static void Displaydata(IEnumerable myvalueList, 
                                          char mySeparator) 
    { 
        foreach(Object obj in myvalueList) 
            Console.Write("{0}{1}", mySeparator, obj); 
        Console.WriteLine(); 
    } 
} 

Output:

Elements are:

Welcome
to
Geeks
for
Geeks
portal

Now elements are:

Welcome
to
This
is
C#
tutorial

Example 2:

// C# program to illustrate the 
// concept of GetRange() Method 
using System; 
using System.Collections; 
  
class GFG { 
  
    // Main method 
    public static void Main() 
    { 
  
        // Creates and initializes a new ArrayList. 
        ArrayList myarraylist = new ArrayList(); 
        myarraylist.Add("Welcome"); 
        myarraylist.Add("to"); 
        myarraylist.Add("Geeks"); 
        myarraylist.Add("for"); 
        myarraylist.Add("Geeks"); 
        myarraylist.Add("portal"); 
  
        // Creates and initializes queue 
        Queue mynewList = new Queue(); 
        mynewList.Enqueue("This"); 
        mynewList.Enqueue("is"); 
        mynewList.Enqueue("C#"); 
        mynewList.Enqueue("tutorial"); 
  
        // Displays the values of six elements 
        ArrayList newarraylist = myarraylist.GetRange(-1, 6); 
        Console.WriteLine("Elements are:"); 
        Displaydata(newarraylist, '\n'); 
  
        // Replaces the values of six elements  
        // starting at index 1 with the  
        // values in the queue. 
        myarraylist.SetRange(2, mynewList); 
  
        // Displays the values of six  
        // elements starting at index 0. 
        newarraylist = myarraylist.GetRange(0, 6); 
        Console.WriteLine("Now elements are:"); 
        Displaydata(newarraylist, '\n'); 
    } 
  
    public static void Displaydata(IEnumerable myvalueList,  
                                          char mySeparator) 
    { 
        foreach(Object obj in myvalueList) 
            Console.Write("{0}{1}", mySeparator, obj); 
        Console.WriteLine(); 
    } 
} 

Runtime Error:

Unhandled Exception:
System.ArgumentOutOfRangeException: Non-negative number required.
Parameter name: index

Reference:

https://docs.microsoft.com/en-us/dotnet/api/system.collections.arraylist.getrange?view=netframework-4.7.2#System_Collections_ArrayList_GetRange_System_Int32_System_Int32_

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