print last three chars of filename

Hello - I have a list of filenames which always end with the authors' initials preceding the extension (e.g., GM_video_9_HLL.TXT). I need to read in just the initials like this

output = dir('*.TXT');

for k = 1:numel(output)

    initials = (output(k).name(19:21));
end

fid = fopen('fields_test1.txt','wt');

fprintf(fid,'OPEN\n');

fprintf(fid,'------------\n');

fprintf(fid,'Field(' , initials , ')\n');

fclose(fid);

The problem is the last three letters are not always at space 19:21 as in the example but they are always the last three letters before the extension in the filenames. Any help would be very much appreciated!

Thank you

Answer 1

[Steven]

filename(end-3:end)

Answer 2

[Image Analyst]

initials = output(k).name(end-6:end-4);

[Gmc]

Thank you!