C#学习笔记之——动态数组(ArrayList)

动态数组

ArrayList只能是一维，Array可以是多维的

• 动态的增加和减少元素
• 实现了ICollection和List和IEnumerable接口
• 灵活的设置数组大小
• 不安全的集合类型
• 其元素为值类型时效率不高(装箱和拆箱导致效率不高)

ArrayList常用的方法

 //to create an ArrayList
		ArrayList arrayList = new ArrayList();


		//to add values
		arrayList.Add(32);
		arrayList.Add("Puma");
		arrayList.Add('a');
		//ArrayList can have different kinds of type of value

		//to output
		foreach (object obj in arrayList)
		{
			Console.Write(obj + " ");
		}
		Console.WriteLine();

		//show the capacity
		Console.WriteLine("the Capacity is:" + arrayList.Capacity);
		Console.WriteLine("Adding one more element");
		arrayList.Add(5);
		Console.WriteLine("Now the Capacity is:" + arrayList.Capacity);


		//count: gets the number of elements actually contained in ArrayList
		Console.WriteLine("The elements in the ArrayList are:" + arrayList.Count);


		//contains : Determines whether an element is in the ArrayList
		if(arrayList.Contains(32))
			Console.WriteLine("It exists!");
		else
			Console.WriteLine("It doesn'n exist");


		//Insert: Insert an element into ArrayList at the specified index
		arrayList.Insert(2,"real");
		foreach (object obj in arrayList)
		{
			Console.Write(obj + " ");
		}
		Console.WriteLine();


		//IndexOf：searches for the specified object and returns the zero-based index of the first occurrence within the entire ArrayList.
		Console.WriteLine(arrayList.IndexOf(32));


		//Remove:Removes the first occurrence of a specific object from the ArrayList
		arrayList.Remove(32);
		foreach (object obj in arrayList)
		{
			Console.Write(obj + " ");
		}
		Console.WriteLine();


		//Reverse:Reverses the order of the elements in the entire ArrayList
		arrayList.Reverse();
		foreach (object obj in arrayList)
		{
			Console.Write(obj + " ");
		}
		Console.WriteLine();


		//Sort:Sorts the elements in the entire ArrayList.
		arrayList.Add(3);
		arrayList.Add(42);
		arrayList.Remove("Puma");
		arrayList.Remove("real");
		arrayList.Remove('a');
		//before sorting
		foreach (object obj in arrayList)
		{
			Console.Write(obj + " ");
		}
		Console.WriteLine();
		arrayList.Sort();
		//after sorting
		foreach (object obj in arrayList)
		{
			Console.Write(obj + " ");
		}
		Console.WriteLine();