For creating .txt files, there are various ways including save (with '-ascii' option), writatable, writematrix, writecell and fopen (with 'w' option) so on.
Here is a sample in Button pushed callback function.
% Button pushed function: GenerateButton
function GenerateButtonPushed(app, event)
p = rand(1,10);
[file,path] = uiputfile('out.txt');
save(fullfile(path, file), 'p', '-ascii')
end
