How can I check the contents of a MAT-file in MATLAB without loading it?

Question

I have a large structure in a MAT-file. I want to check if a specific field is present in the structure without loading the MAT-file since the contents are very large and I want to minimize memory use.

Is this possible, or must I load it first like in the following example?:

load('test.mat');             %# Load the MAT-file
tf = isfield(s,'fieldname');  %# Check if structure s has field 'fieldname'

Answer 1

To check the contents of a MAT file without loading it, use:

vars = whos('-file','test.mat')
ismember('fieldname', {vars.name})

Answer 2

As far as I know, you have to load the file in order to be able to check if a saved structure contains a specific field.

However, if you save the .mat file with the '-struct'-option, it splits the fields into separate variables in the .mat file. You can recreate the structure by calling

myStructure = load('test.mat');

Saving this way also allows you to test for whether a field (variable) exists by using @Amro's approach (which is a lot cleaner than what I suggested before).