Create empty array using reflection

Question

How do I create empty array of a type given by reflection? I have tried using the Activator.CreateInstance(Type) method:

Type arrayType = typeof(string[]);
Activator.CreateInstance(arrayType);

but I get a MissingMethodException exception:

System.MissingMethodException: No parameterless constructor defined for this object.

What am I doing wrong?

`Type arrayType = typeof(string[]); Array.CreateInstance(arrayType, 5); or you could write Type arrayType = typeof(System.Array); Array.CreateInstance(arrayType, 5)` — MethodMan, Jan 08 '16 at 18:09

T McKeown · Accepted Answer · 2022-04-26T12:15:18.310

-1

Some types you have to trap and handle special, for your case you'd use:

if ( type.IsArray){
  var o = Array.CreateInstance(type, size);
}

edited Apr 26 '22 at 12:15

answered Jan 08 '16 at 18:00

T McKeown

This answer is clearly wrong. – Mo B. Apr 21 '22 at 12:59
Why is it? The misplaced curlies? – T McKeown Apr 24 '22 at 18:21
`Array.CreateInstance` takes the element type as first parameter, not the array type. – Mo B. Apr 25 '22 at 07:58
Ah.. ok. I'll adjust. – T McKeown Apr 25 '22 at 12:39
In fairness my code sample was coded like that type parameter was implied to mean the type of array element. I was not using the ops code. – T McKeown Apr 25 '22 at 12:57
I've corrected. – T McKeown Apr 25 '22 at 23:08
It's still wrong, you need to call `GetElementType()` on `type`. Right now `o` has type `System.Array[]` which is probably not what you want. – Mo B. Apr 26 '22 at 10:04
Ha.. the point of the answer was to use CreateInstance method and pass the type. And declaring a var o on the ifv statement is also not correct.. I wasn't giving code to use. I was answering the question. – T McKeown Apr 26 '22 at 12:13
I'm on my phone.. and I'm not that interested – T McKeown Apr 26 '22 at 12:26
It's still wrong: it should be `var o = Array.CreateInstance(type.GetElementType(), size)`. – Mo B. Apr 26 '22 at 12:49
Excellent work! Congrats – T McKeown Apr 26 '22 at 13:10
But o is out of scope. – T McKeown Apr 26 '22 at 13:11

1 Answers1