Validation of a date with a given format

Hi. I am designing a GUI. I have an edit text box where I enter a date string with the following format '31 Mar 2011 10:00:00.000'. I need code to validate it and write an error message in case of invalid input. Thank you for your attention. Cheers.

Answer 1

[Julián Francisco]

Thank you all for the answers. This is one of the posible callback function codes corresponding to the edit text box that it can be used:

user_entry = get(hObject,'string');
control = regexp(user_entry,'[0-3]\d (Jan|Feb|Mar|...|Dec) \d\d\d\d (0\d|1[0-2]):[0-5]\d:[0-5]\d.\d\d\d')
if(numel(control)==0)
    errordlg('Invalid Input Format','Error Message','modal')
    uicontrol(hObject)
end

Answer 2

[Matt Fig]

try 
   D = datenum(Inpt,'dd mmm yyyy HH:MM:SS.FFF')
catch
   error('Incorrect Format')
end

[Matt Tearle]

Great minds may think alike, but apparently one types faster than the other :)

[Matt Fig]

I guess so! The only problem with our approach is that Julian may want to be more pedantic than we would be. For example, the user doesn't have to enter exactly 3 places for the millisecond data. If Julian wants this then there will have to be further checks. This would pass our tests:

31 Mar 2011 10:00:00.0

[Julián Francisco]

@Matt Fig: Thank you for your answer. Excuse me for being pedantic. It was not my intention. Cheers.

[Matt Fig]

I wasn't saying you _were_ pedantic, only that as far as I know, you _might_ want to the user to enter in exactly 3 values for the milliseconds position. If you don't care about this, then the code should work fine if the user enters only one value. All else will be checked as you requested....

Answer 3

[Matt Tearle]

fmt = 'dd mmm yyyy HH:MM:SS.FFF';

dt = [];
while isempty(dt)
    x = input(['enter date string in ',fmt,' format: '],'s');
    try
        dt = datenum(x,fmt);
    catch
        disp(['Hey idiot, I said ',fmt,' format'])
    end
end

(Obviously I'm using input in place of the GUI entry, but the basic structure/flow would be the same)

[Julián Francisco]

Thank you for your answer. I grateful your intention of giving the first response. Cheers.

Answer 4

[Walter Roberson]

% 31 Mar 2011 10:00:00.000

Basic validation:

regexp(t, '[0-3]\d (Jan|Feb|Mar|...|Dec) \d\d\d\d (0\d|1[0-2]):[0-5]\d:[0-5]\d.\d\d\d')

Once you've done the basic validation, you can cross-check for consistency such as the maximum day number being appropriate for the month.

[Jan]

Matlab's date functions check the validity sufficiently. If the date string is valid, DaTESTR(DATENUM(STR)) equals STR.

[Julián Francisco]

@Walter Roberson: Thank you for your answer. It looks like to be the shortest one but it needs adittional code to show an error message. Cheers.

[Julián Francisco]

@Jan Simon: Thank you for your suggestion. Cheers.