如何通过索引从 C# 中的 OrderedDictionary 获取键？
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How do I get a key from a OrderedDictionary in C# by index?
提问by Red Swan
How do I get the key and value of item from OrderedDictionary by index?
如何通过索引从 OrderedDictionary 中获取 item 的键和值？
采纳答案by jason
There is not a direct built-in way to do this. This is because for an OrderedDictionarythe index isthe key; if you want the actual key then you need to track it yourself. Probably the most straightforward way is to copy the keys to an indexable collection:
没有直接的内置方法可以做到这一点。这是因为OrderedDictionary索引是关键；如果您想要实际的密钥，那么您需要自己跟踪它。可能最直接的方法是将键复制到可索引集合中：
// dict is OrderedDictionary
object[] keys = new object[dict.Keys.Count];
dict.Keys.CopyTo(keys, 0);
for(int i = 0; i < dict.Keys.Count; i++) {
Console.WriteLine(
"Index = {0}, Key = {1}, Value = {2}",
i,
keys[i],
dict[i]
);
}
You could encapsulate this behavior into a new class that wraps access to the OrderedDictionary.
您可以将此行为封装到一个新类中，该类包含对OrderedDictionary.
回答by Martin R-L
orderedDictionary.Cast<DictionaryEntry>().ElementAt(index);
回答by Halcyon
I created some extension methods that get the key by index and the value by key using the code mentioned earlier.
我创建了一些扩展方法，它们使用前面提到的代码按索引获取键和按键获取值。
public static T GetKey<T>(this OrderedDictionary dictionary, int index)
{
if (dictionary == null)
{
return default(T);
}
try
{
return (T)dictionary.Cast<DictionaryEntry>().ElementAt(index).Key;
}
catch (Exception)
{
return default(T);
}
}
public static U GetValue<T, U>(this OrderedDictionary dictionary, T key)
{
if (dictionary == null)
{
return default(U);
}
try
{
return (U)dictionary.Cast<DictionaryEntry>().AsQueryable().Single(kvp => ((T)kvp.Key).Equals(key)).Value;
}
catch (Exception)
{
return default(U);
}
}
