C# 如何按字母顺序遍历Hashtable的键？
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How to traverse keys of a Hashtable in alphabetical order?
提问by Pavel Bastov
What is the easiest way to traverse a hashtable's keys in ascending alphabetical order?
按字母升序遍历哈希表键的最简单方法是什么？
采纳答案by JaredPar
This is fairly dependent upon what the type of the key is. But lets assume for a minute that they are strings. You could use the following LINQ query
这相当依赖于密钥的类型。但是让我们假设它们是字符串。您可以使用以下 LINQ 查询
Hashtable table = GetHashTable();
var keys = table.Keys.Cast<String>().OrderBy(x => x);
For more complex structures the LINQ query is only slightly different. Lets assume you had the following definition for a key
对于更复杂的结构，LINQ 查询只是略有不同。让我们假设您对密钥有以下定义
struct Name {
public string First;
public string Last;
// Equality code omitted
}
The LINQ code would be the following
LINQ 代码如下
Hashtable table = GetHashtable();
var keys = table.Keys.Cast<Name>().OrderBy(x => x.First).ThenBy(x => x.Last);
回答by JH.
Thats not really what hash tables are designed for (they are made to have uniform distribution of keys). Use a sorted tree?
那并不是真正为哈希表设计的（它们被设计为具有均匀的键分布）。使用排序树？
回答by Jon Skeet
If you want a map which keeps its keys in natural order, I suggest you don't use Hashtableto start with. If you're still using 1.1, using System.Collections.SortedList. If you're using 2.0 or higher, use SortedList<TKey, TValue>or SortedDictionary<TKey, TValue>. The latter two are largelythe same in terms of API, but have different performance characteristics - see the docs for more information.
如果您想要一个按自然顺序保存其键的地图，我建议您不要使用Hashtable开始。如果您仍在使用 1.1，请使用System.Collections.SortedList. 如果您使用的是 2.0 或更高版本，请使用SortedList<TKey, TValue>或SortedDictionary<TKey, TValue>。后两者在 API 方面基本相同，但具有不同的性能特征 - 有关更多信息，请参阅文档。
回答by Pavel Bastov
Well, I found this snippet to be the most suitable to my situation:
好吧，我发现这个片段最适合我的情况：
Hashtable settings = GetSettings();
ArrayList keys = new ArrayList();
keys.AddRange(settings.Keys);
keys.Sort();
foreach (object key in keys)
{
// Logic here
}
回答by thecoop
It'll probably be slightly faster to use SortedList -
使用 SortedList 可能会稍微快一点 -
SortedList settings = new SortedList(GetSettings());
foreach (object key in settings.Keys)
{
//logic
}
creating & sorting the ArrayList is O(n) + O(nlog n) = O(nlog n), whereas the SortedList constructor (according to the docs) is O(n), so it'll be faster to use SortedList directly rather than using an arraylist and explicitly sorting
创建和排序 ArrayList 是 O(n) + O(nlog n) = O(nlog n)，而 SortedList 构造函数（根据文档）是 O(n)，因此直接使用 SortedList 会更快比使用数组列表并显式排序
