差异黑白哈希表和字典 [英] diff. b/w hashtable and dictionary

问题描述

我想知道到底是什么差异.哈希表和带有示例的字典.

i want to know what is exactly diff. hashtable and dictionary with example.
thanks in advance.

推荐答案

非常粗略:类System.Collections.Hashtable是过时的版本，其功能与通用类System.Collections.Generic.Dictionary非常相似在.NET Framework v.2.0中实现之前创建的通用类.

该类没有用obsolete属性正式标记，因为它没有任何问题.可以在旧代码中使用它，但是在新代码中使用它是完全没有意义的.泛型更好，因为您不需要使用容易出错的类型转换.而是从这三个类System.Collections.Generic.Dictionary，System.Collections.Generic.SortedDictionary或System.Collections.Generic.SortedList， http://msdn中选择.microsoft.com/en-us/library/0sbxh9x2.aspx [ ^ ].

它们的实现方式不同，但是从使用代码的角度来看，它们的主要区别在于性能和冗余之间的不同权衡.

—SA

Very roughly: the class System.Collections.Hashtable is obsolete version with functionality very similar to the generic class System.Collections.Generic.Dictionary created before generic were implemented in v.2.0 of the .NET Framework.

This class was not formally marked by the obsolete attribute, because there is nothing wrong with it; and it can be used in legacy code, but using it in new code is totally pointless. Generics are way better, because you don''t need to use error-prone typecasts. Instead, choose from these three classes System.Collections.Generic.Dictionary, System.Collections.Generic.SortedDictionary or System.Collections.Generic.SortedList, http://msdn.microsoft.com/en-us/library/0sbxh9x2.aspx[^].

They are different in implementations, but, from the standpoint of the using code, they are different mainly in the different trade-off between performance and redundancy.

—SA

下面的链接为您提供了您想要的所有区别，但是，我会在发布之前尝试找到自己的答案:

http://msdn.microsoft.com/en-us/library/4yh14awz.aspx [ ^ ]

Below link provides you all the differences you want, however, i would try to find answers my self before posting:

http://msdn.microsoft.com/en-us/library/4yh14awz.aspx[^]

A Dictionary是Hashtable的通用版本. 在Hashtable中，您只能将object作为键和值添加.
在Dictionary中，可以选择键的类型和值:

A Dictionary is a generic version of a Hashtable.
In a Hashtable, you can only add objects as a key and a value.
In a Dictionary, you can choose the type for the key and for the value:

Hashtable hashtable1 = new Hashtable();
           hashtable1.Add(1, "HashtableValue1"); // add a key/value pair to the Hashtable
           Dictionary<int,> dictionary1 = new Dictionary<int,>();
           dictionary1.Add(1, "DictionaryValue1"); // add a key/value pair to the Dictionary
           string hashtableValue1 = (string)hashtable1[1]; // get the value of the Hashtable and cast it to a string
           string dictionaryValue1 = dictionary1[1]; // get the value of the Dictionary, you don't need to cast the value to a string

希望这会有所帮助.

Hope this helps.

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