Why can't I compare a KeyValuePair with default

Question

In .Net 2.5 I can usually get an equality comparison (==) between a value and its type default

if (myString == default(string))

However I g

Answer 1

This happens because KeyValuePair does not define a custom == operator and is not included in the predefined list of value types that can use it.

Here is a link to the MSDN documentation for that operator.

For predefined value types, the equality operator (==) returns true if the values of its operands are equal, false otherwise.

Your best bet for an equality check in this case, because this is not a struct you have control over, is to call default(KeyValuePair).Equals(pair) instead.