Looking for a more elegant way to check for nullable value types

Question

To check if a value type is nullable I'm currently doing something like this:

int? i = null;
bool isNullable = i.GetType().ToString().Contains("System.Nullable");

Is there a more elegant way to do this?

Answer 1

You can use Nullable.GetUnderlyingType(Type) - that will return null if it's not a nullable type to start with, or the underlying value type otherwise:

if (Nullable.GetUnderlyingType(t) != null)
{
    // Yup, t is a nullable value type
}

Note that this uses the Nullable static class, rather than the Nullable<T> structure.

Answer 2

if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
{
  // it is a nullable type
}

This is how Microsoft recommends you Identify Nullable Types