If statement error in gui.

Hi, I have an input box so that the user would input a number ranging 1 to 300. if he put more than 300 and less than one error pop out. this is my code:

a = (str2num(get(handles.Th,'String'))
if (a < 1 & a >= 300);
    warndlg('Pressing OK will clear memory','!! Warning !!')
end

Answer 1

[Walter Roberson]

There is no value of "a" which is simultaneously less than 1 and greater than or equal to 300.

if a < 1 | a >= 300     %finds values outside the range [1, 300)

if a > 1 & a <= 300     %finds values inside the range (1, 300]

Answer 2

[Image Analyst]

You need to wrap that warndlg() inside a uiwait() otherwise it will go blasting past that and execute more code before they can click OK. Here is some code I use to validate an entry and assign a default in case the user entered an invalid entry.

% Ask user for one integer number.
defaultValue = 45;
titleBar = 'Enter an integer value';
userPrompt = 'Enter the integer';
caUserInput = inputdlg(userPrompt, titleBar, 1, {num2str(defaultValue)});
if isempty(caUserInput),return,end; % Bail out if they clicked Cancel.
% Round to nearest integer in case they entered a floating point number.
userValue = str2double(cell2mat(caUserInput));
% Check for a valid integer.
if isnan(userValue)
    % They didn't enter a number.  
    % They clicked Cancel, or entered a character, symbols, or something else not allowed.
    userValue = defaultValue;
    message = sprintf('I said it had to be an integer.\nI will use %d and continue.', userValue);
    uiwait(warndlg(message));
end

Of course one of the modifications you'd do is to, after my "if", add an "elseif" to check on a and warn the user if they did something boneheaded:

elseif (a < 1 || a >= 300)
    message = sprintf('a must be between 1 and 300, not %f.', userValue);
    uiwait(warndlg(message));

[EJ Ardiente]

Thank you for making the code not complicated. :)

[Image Analyst]

You're welcome. I always try to use lots of comments, even for things that I think should be pretty obvious. I wish everyone would use comments, but sadly most people don't.