Adding fields to a struct?

I have an existing struct titled PR1Data. I would like to add a new field titled 'filename' to the structure, why is this so difficult to do? I only want the field to exist, i have tried the following methods with no results:

PR1Data=setfield(PR1Data,'filename',[1 2])

error: 'scalar structure required for this assignment'

PR1Data.filename='';

Same error

How can i simply add a new field to an existing struct?? this should not be this difficult

Answer 1

[Bruno Luong]

[PR1Data.filename] = deal('');

or if you PR1Data is non empty

PR1Data(1).filename = '';