Question

I want to set the initial size of a dictionary using Activator.CreateInstance, what is the syntax please?

var collection = Activator.CreateInstance(someDictionaryType) as IDictionary; 

Answer 1

If you would like to call a Dictionary constructor with an int parameter representing capacity, pass an object array with a single element – the size:

var collection = Activator.CreateInstance(someDictionaryType, new object[] {123}) as IDictionary;