[C#] 主要容器及其数据结构

C# 容器可以分为无Generic时代 和 Generic时代。Generic是C# 2.0时的产物。

在System.Collections.Generic，也就是泛型命名空间出现以前。常用的是System.Collections 命名空间下的容器，包括ArrayList，Stack, SortedList, Queue等等。这些容器有一个共同特点：其存储的元素都是object。这就意味着，比如ArrayList，它可以同时存放各种类型的数据，因为所有的类型都会转化为object存储，访问元素时会自动提出数据。这样的过程，我们称其为“装箱”和“拆箱”(boxing and unboxing)。

因此，System.Collections中的容器好处在于：不是严格类型的，可以放不同类型的值。坏处在于：因为对存放数据没有类型要求，所以不是类型安全的；另外，装箱和拆箱会是一个很耗费时间的工作。

 

arraylist vs List<> in c#

http://stackoverflow.com/questions/2309694/arraylist-vs-list-in-c-sharp

List<T> is a generic class. It supports storing values of a specific type without casting to or from object (which would have incurred boxing/unboxing overhead when T is a value type in the ArrayList case). ArrayList simply stores object references. As a generic collection, it implements the generic IEnumerable<T> interface and can be used easily in LINQ (without requiring any Cast or OfType call).

ArrayList belongs to the days that C# didn't have generics. It's deprecated in favor of List<T>. You shouldn't use ArrayList in new code that targets .NET >= 2.0 unless you have to interface with an old API that uses it.

引申出generic。

引申出LINQ，

 

List<T> 等属于 Generics，Arraylist等属于早期的容器

The List<T> class is the generic equivalent of the ArrayList class. It implements the IList<T> generic interface by using an array whose size is dynamically increased as required.

 

我们都知道List<T>的Add是O(1)的操作，但之所以它是O(1)，是因为它的“扩容”操作被均摊了（amortized），但每次扩容时其实还是需要复制所有元素，次数越少越好

http://blog.zhaojie.me/2013/01/think-in-detail-why-its-o-1.html

 

In deciding whether to use the List<T> or ArrayList class, both of which have similar functionality, remember that the List<T> class performs better in most cases and is type safe. If a reference type is used for type T of the List<T> class, the behavior of the two classes is identical. However, if a value type is used for type T, you need to consider implementation and boxing issues.

来自http://msdn.microsoft.com/en-us/library/6sh2ey19(v=vs.110).aspx

衍生出装箱和拆箱。。。

 

Benefits of Generics

http://msdn.microsoft.com/en-us/library/b5bx6xee.aspx

 

LINQ Query

http://www.cnblogs.com/greenerycn/archive/2010/10/22/linq_intro.html