C# |从源数组列表中获取元素的子集

原文:https://www . geeksforgeeks . org/c-sharp-从源数组列表中获取元素子集/

数组列表。GetRange(Int32，Int32)方法用于获取一个数组列表，它将代表源数组列表中元素的子集。

语法:

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

参数:

索引:为 Int32 类型，代表范围开始的从零开始的数组列表索引。 计数:为 Int32 型，代表该范围内的元素数量。

返回值:该方法返回一个数组列表，该列表代表源数组列表中元素的子集。

异常:

  • argumentoutofrangerexception:如果索引的值小于零， 或者 如果计数的值小于零。
  • 参数异常:如果索引和计数的值不表示数组列表中元素的有效范围。

以下程序说明了上述方法:

例 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();
    }
}

输出:

Elements are:

Welcome
to
Geeks
for
Geeks
portal

Now elements are:

Welcome
to
This
is
C#
tutorial

例 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();
    }
}

运行时错误:

未处理异常: 系统。ArgumentOutOfRangeException:要求非负数。 参数名称:索引

参考:

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