IF statement restarting when condition is true

hello i make an IF statement:

d=input('Is this spur gear mounted between two bearing? (Y/N): ','s');
if d=='N' 
    error('this program is not for you');  
elseif d~='Y' | d~='N'
    disp('you must use capital letters')
    return
end

i would, if the second condition is true, to restart the code from

d=input('...

how can i do this?

Answer 1

[Rick Rosson]

k = [];  
while isempty(k)
    d=input('Is this spur gear mounted between two bearing? (Y/N): ','s');
    k = findstr(upper(d),'YN');
    if isempty(k)
         fprintf('Invalid response.  Please try again.\n');
    end
end