.Net Tips – Getting the default value of a type outside of generics

To get the default value of a type, you’ve probably used the default keyword in .Net already:

   1: var defaultInt = default(int);        // 0

   2: var defaultObj = default(string);     // null

However, the use of the default keyword requires a type name to be specified at compile time, so you won’t be able to use it on a type which you discover at runtime. Instead, you will need to do something along the line of:

   1: public object GetDefaultValue(Type type)

   2: {

   3:     // Handle value types and reference types differently

   4:     if (type.IsValueType)

   5:     {

   6:         return Activator.CreateInstance(type);

   7:     }

   8:     else

   9:     {

  10:         return null;

  11:     }

  12: }

It’ll yield the same result as using the default keyword:

   1: var defaultInt = GetDefaultValue(typeof(int));        // 0

   2: var defaultObj = GetDefaultValue(typeof(string));     // null

Enjoy what you’re reading? Subscribe to my newsletter and get more content on AWS and serverless technologies delivered straight to your inbox.


Yan Cui

I’m an AWS Serverless Hero and the author of Production-Ready Serverless. I have run production workload at scale in AWS for nearly 10 years and I have been an architect or principal engineer with a variety of industries ranging from banking, e-commerce, sports streaming to mobile gaming. I currently work as an independent consultant focused on AWS and serverless.

You can contact me via Email, Twitter and LinkedIn.

Hire me.


Check out my new course, Complete Guide to AWS Step Functions.

In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. Including basic concepts, HTTP and event triggers, activities, design patterns and best practices.

Get Your Copy