Variable type ending with ?
.net, c#, nullable, types
Solution
`?` makes your non-nullable (value) types nullable. It doesn't work for `string`, as it is reference type and therefore nullable by default.
From MSDN, about value types:
Unlike reference types, a value type cannot contain the null value. However, the nullable types feature does allow for values types to be assigned to null.
`?` is basically a shorthand for `Nullable<T> structure`.
If you want to know more, MSDN has a great article regarding this topic.
Problem
What does `?` mean: ``` public bool? Verbose { get; set; } ``` When applied to `string?`, there is an error: The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable'