c# - .NET DefaultValue attribute

Question

I've heard people say a few different things about the DefaultValue attribute including:

• "It sets the value of the property before anything else uses it."
• "It doesn't work for autoproperties."
• "It's only for decoration. You must manually set actual default values."

Which (if any) is right? Does DefaultValue actually set default values? Are there cases where it doesn't work? Is it best just not to use it?

Answer 1

The place where I typically used DefaultValue is for classes which are serialized/deserialized to XML. It does not set the default value during instantiation and doesn't impact autoproperties.

From MSDN:

A DefaultValueAttribute will not cause a member to be automatically initialized with the attribute's value. You must set the initial value in your code.

MSDN - DefaultValueAttribute Class

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Edit: As Roland points out, and as others mentioned in their answers the attribute is also used by the Form Designer