C# KeyValuePair VS DictionaryEntry
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KeyValuePair VS DictionaryEntry
提问by Jaywith.7
What is the difference between KeyValuePair which is the generic version and DictionaryEntry?
通用版本的 KeyValuePair 和 DictionaryEntry 有什么区别？
Why KeyValuePair is used instead of DictionaryEntry in generic Dictionary class?
为什么在通用 Dictionary 类中使用 KeyValuePair 而不是 DictionaryEntry？
回答by Chris
KeyValuePair < T,T > is for iterating through Dictionary < T,T >. This is the .Net 2 (and onwards) way of doing things.
KeyValuePair < T,T > 用于遍历 Dictionary < T,T >。这是 .Net 2（及以后）的做事方式。
DictionaryEntry is for iterating through HashTables. This is the .Net 1 way of doing things.
DictionaryEntry 用于遍历 HashTables。这是 .Net 1 的做事方式。
Here's an example:
下面是一个例子：
Dictionary<string, int> MyDictionary = new Dictionary<string, int>();
foreach (KeyValuePair<string, int> item in MyDictionary)
{
// ...
}
Hashtable MyHashtable = new Hashtable();
foreach (DictionaryEntry item in MyHashtable)
{
// ...
}
回答by cdmckay
KeyValuePair<TKey,TValue>is used in place of DictionaryEntrybecause it is generified. The advantage of using a KeyValuePair<TKey,TValue>is that we can give the compiler more information about what is in our dictionary. To expand on Chris' example (in which we have two dictionaries containing <string, int>pairs).
KeyValuePair<TKey,TValue>被用来代替 ofDictionaryEntry因为它是泛型的。使用 a 的好处KeyValuePair<TKey,TValue>是我们可以为编译器提供更多关于字典中内容的信息。扩展克里斯的例子（其中我们有两个包含<string, int>对的字典）。
Dictionary<string, int> dict = new Dictionary<string, int>();
foreach (KeyValuePair<string, int> item in dict) {
int i = item.Value;
}
Hashtable hashtable = new Hashtable();
foreach (DictionaryEntry item in hashtable) {
// Cast required because compiler doesn't know it's a <string, int> pair.
int i = (int) item.Value;
}
