Question

I have a property like this:

public Tuple<String, String>[] Breadcrumbs { get; set; }

and I have a test in one of my methods like this:

if (Breadcrumbs != null && Breadcrumbs.Length > 0) { }

Depending on when this method is called, Breadcrumbs may not have been set. In one test, Breadcrumbs == null evaulates to true.

Will unset properties always have a value? (Will it always be null?)

Answer 1

An automatically-implemented property which hasn’t been explicitly set by any code will always have the default value for the property type – which is null for reference types. (For int it would be 0, for char it would be ‘\0’ etc).

An automatically implemented property like this is just equivalent to:

private PropertyType property;
public PropertyType Property
{
    get { return property; }
    set { property = value; }
}

… except that the backing variable has an unspeakable name (you can’t refer to it in code) so it will always start off with the default value for the type.