Testing for equality between dictionaries in C#

Question

Assuming dictionary keys and values have their equals and hash methods implemented correctly, what is the most succinct and efficient way to test for equality of two dictionaries?

In this context, two dictionaries are said to be equal if they contain the same set of keys (order not important), and for every such key, they agree on the value.

Here are some ways I came up with (there are probably many more):

public bool Compare1<TKey, TValue>(     Dictionary<TKey, TValue> dic1,      Dictionary<TKey,TValue> dic2) {     return dic1.OrderBy(x => x.Key).         SequenceEqual(dic2.OrderBy(x => x.Key)); }  public bool Compare2<TKey, TValue>(     Dictionary<TKey, TValue> dic1,      Dictionary<TKey, TValue> dic2) {     return (dic1.Count == dic2.Count &&          dic1.Intersect(dic2).Count().         Equals(dic1.Count)); }  public bool Compare3<TKey, TValue>(     Dictionary<TKey, TValue> dic1,      Dictionary<TKey, TValue> dic2) {     return (dic1.Intersect(dic2).Count().         Equals(dic1.Union(dic2).Count())); } 

Answer 1

dic1.Count == dic2.Count && !dic1.Except(dic2).Any();