How to check if object is an array of a certain type?

Question

This works fine:

var expectedType = typeof(string);
object value = "...";
if (value.GetType().IsAssignableFrom(expectedType))
{
     ...
}

But how do I check if value is a string array without setting expectedType to typeof(string[])? I want to do something like:

var expectedType = typeof(string);
object value = new[] {"...", "---"};
if (value.GetType().IsArrayOf(expectedType)) // <---
{
     ...
}

Is this possible?

Answer 1

Use Type.IsArray and Type.GetElementType() to check the element type of an array.

Type valueType = value.GetType();
if (valueType.IsArray && expectedType.IsAssignableFrom(valueType.GetElementType())
{
 ...
}

Beware the Type.IsAssignableFrom(). If you want to check the type for an exact match you should check for equality (typeA == typeB). If you want to check if a given type is the type itself or a subclass (or an interface) then you should use Type.IsAssignableFrom():

typeof(BaseClass).IsAssignableFrom(typeof(ExpectedSubclass))

Answer 2

You can use extension methods (not that you have to but makes it more readable):

public static class TypeExtensions
{
    public static bool IsArrayOf<T>(this Type type)
    {
         return type == typeof (T[]);
    }
} 

And then use:

Console.WriteLine(new string[0].GetType().IsArrayOf<string>());