User input with 3 options, how to repeat question if one of the options was not entered.

I am trying to add something to the end of a function that will be looped over and over to ask the user whether they are happy with the results, at which they can type 'yes', 'no', or 'trash'. If the user types something else the question should be repeated until one of these options is entered. I tried to use the code:

UI = 'aaa'
while UI ~= 'yes' & UI ~= 'no' & UI ~= 'trash' %ERROR AT THIS LINE
  UI = input("Are you happy with this? Enter: 'yes' 'no'(to manually change) or 'trash' skip and move onto next unit.", 's')
end
if UI == 'yes'
  % do something
  return
elseif UI == 'no'
  % do something
else UI == 'trash'
  % do something else
end

I have tried the while loop with both '&' and '&&' and neither works, was wondering if anyone could help me out, thanks.

Answer 1

[Geoff Hayes]

Sean - use strcmpi when comparing strings else you will see errors like

 Error using  ~= 
 Matrix dimensions must agree.

when comparing strings like how you are doing. Your code would then become

 UI = [];
 while ~strcmpi(UI,'yes') && ~strcmpi(UI,'no') && ~strcmpi(UI,'trash') %ERROR AT THIS LINE
      UI = input('Are you happy with this? Enter: ''yes'' ''no''(to manually change) or ''trash'' skip and move onto next unit.', 's');
 end

Note how single quotes are used (instead of double quotes) to wrap your string and that we use two single quotes on either side of (say) yes so that the single quotes appear in the output string.

Try the above and see what happens!

Answer 2

[Image Analyst]

Then don't do it that way. Use questdlg() like you're supposed to:

promptMessage = sprintf('Do you want to Continue processing,\nor Quit processing?');
titleBarCaption = 'Continue?';
buttonText = questdlg(promptMessage, titleBarCaption, 'Continue', 'Quit', 'Continue');
if strcmpi(buttonText, 'Quit')
  return; % or break or continue - whatever is appropriate.
end