how to prevent input dialog box be closed in matlab? - matlab

Question

how can the input dialog box can be avoided from directly close by the user without enter any value? for the 'menu' function we can form loop using while options==0 for unselected options but how about input dialog?
prompt = {'Enter gain:','Enter range:'};
dlg_title = 'Enter values';
num_lines= 1;
def = {'20','256'}; %default
answer = inputdlg(prompt,dlg_title,num_lines,def);
%%%to get the two entered values%%%%
%A = getfield(answer,{1}); %first input field
A = str2double(answer{1});
%B = getfield(answer,{2}); %second input field
B = str2double(answer{2});
suppose I have a input dialog as shown, how I can model it with the loop in complete way

Answer 1

You cannot prevent it from being closed, but you can use a while-loop to re-open it until the user has entered a useful value.
done = false;
while ~done
a=inputdlg('enter a number')
num = str2double(a{1}); %# will turn empty and strings into NaN
if isnumeric(num)
done = true;
else
%# keep running while loop
%# you can pop up an errordlg box here to tell the user what was wrong.
%# It would be nice if you were to set the inputs that passed the test
%# as defaults for the next call of inputdlg. Nothing sucks as much
%# as having to completely re-fill a form because of a small typo
end
end