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如何在C#中创建ArrayList?用法示例

ArrayList()构造函数用于初始化ArrayList类的新实例, 该实例将为空并具有默认的初始容量。数组列表表示可以单独索引的对象的有序集合。它基本上是数组的替代方法。它还允许动态分配内存, 添加, 搜索和排序列表中的项目。

语法如下:

public ArrayList ();

重要事项:

  • ArrayList可以容纳的元素数称为容量ArrayList。如果将元素添加到ArrayList中, 则将通过重新分配内部数组来自动增加容量。
  • 如果可以估计集合的大小, 则指定初始容量将消除在将元素添加到ArrayList时执行大量调整大小操作的需求。
  • 此构造函数是O(1)操作。

示例1:

//C# Program to illustrate how
//to create a ArrayList
using System;
using System.Collections;
  
class Geeks {
  
     //Main Method
     public static void Main(String[] args)
     {
  
         //arrlist is the ArrayList object
         //ArrayList() is the constructor
         //used to initializes a new
         //instance of the ArrayList class
         ArrayList arrlist = new ArrayList();
  
         //Count property is used to get the
         //number of elements in ArrayList
         //It will give 0 as no elements
         //are present currently
         Console.WriteLine(arrlist.Count);
     }
}

输出如下:

0

示例2:

//C# Program to illustrate how
//to create a ArrayList
using System;
using System.Collections;
  
class Geeks {
  
     //Main Method
     public static void Main(String[] args)
     {
  
         //arrlist is the ArrayList object
         //ArrayList() is the constructor
         //used to initializes a new
         //instance of the ArrayList class
         ArrayList arrlist = new ArrayList();
  
         Console.Write( "Before Add Method: " );
  
         //Count property is used to get the
         //number of elements in ArrayList
         //It will give 0 as no elements
         //are present currently
         Console.WriteLine(arrlist.Count);
  
         //Adding the elements
         //to the ArrayList
         arrlist.Add( "This" );
         arrlist.Add( "is" );
         arrlist.Add( "C#" );
         arrlist.Add( "ArrayList" );
  
         Console.Write( "After Add Method: " );
  
         //Count property is used to get the
         //number of elements in arrlist
         Console.WriteLine(arrlist.Count);
     }
}

输出如下:

Before Add Method: 0
After Add Method: 4

参考:

  • https://docs.microsoft.com/zh-cn/dotnet/api/system.collections.arraylist.-ctor?view=netframework-4.7.2#System_Collections_ArrayList__ctor

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