MATLAB: Does the function DATEVEC in MATLAB 7.5 (R2007b) return incorrect results when no format is supplied

MATLAB

I use the following code:

dv = datevec('20/11/2007')
datestr(dv)

The resultant output is

ans =
26-Jan-0000
04-Jan-0000
30-Jan-0000
00-Jan-0000
00-Jan-0000
00-Jan-0000

In MATLAB 7.4 (R2007a)

dv = datevec('20/11/2007')

would correctly result in the following error

 Error using ==> datevec at 259
 20 is too large to be a month.

Best Answer

This is expected behavior. The DATEVEC function does its best to guess the date in the absence of a format string, but it is only guaranteed to do so for certain formats, and dd/mm/yyyy is not one of them.

To work around this issue, pass the format of the input date string as follows:

dv = datevec('20/11/2007','dd/mm/yyyy')
datestr(dv)

For detailed information on the various date formats please refer the MATLAB documentation for the function DATESTR by entering the following at the MATLAB command prompt:

doc datestr

Related Solutions

MATLAB: Does DATESTR return an error when parsing date strings with non-US local time/date formats in MATLAB 7.5 (R2007b)

MATLAB does not support converting non-standard date strings to other date strings directly using DATESTR.

Instead, use the following syntax to explicitly specify the format of the input date string. The commands,

DN = datenum('21-Dez-2007 09:30:20', 'dd-mmm-yyyy HH:MM:SS');
dStr = datestr(DN, 31, 'local')

return, as expected,

 dStr =
 2007-12-21 09:30:20

Although some combinations of locales and formats may occassionally return correct results using the single-line DATESTR call, MATLAB does not support direct conversion between a date string and another string.

For more information on the DATESTR and DATENUM functions, please consult the documentation by executing the following at the MATLAB Command prompt:

doc datestr
doc datenum

MATLAB: Does DATENUM give me an error message when I pass German date strings as input arguments in MATLAB

In MATLAB 7.5 (R2007b), date strings are derived from the locale settings set by the user on the system. The Locale Settings are available from:

Start -> Settings -> Control Panel -> Regional and Language Settings

DATENUM uses a locale database that may or may not be the same as the locale settings on your system. Therefore, DATENUM is sometimes unable to recognize date strings originating from locale settings.

To work around this issue, use the "datenum" field on the structure variable returned by the DIR command. For example:

d = dir;
d.datenum

will produce the corresponding serial date numbers of the file time stamps in MATLAB.

Historical information about the behavior of MATLAB R14SP3 through R2008b:

1. The MATLAB releases R14SP3, R2006a and R2006b do not include a "datenum" field in the structure returned by the function DIR. The field "date" returns the date in English format.

2. The MATLAB release R2007a includes a "datenum" field in the structure returned by the function DIR for the first time. The field "date" still returns the date in English format.

3. Starting with MATLAB release R2007b, the "datenum" field is included in the structure returned by the function DIR, but the field "date" returns the date by using the format specified in the system locale settings.

Here's an example for a machine that uses German system locale settings:

 - R14SP3, R2006a, R2006b
 ------------------------------
 >> d = dir
 d = 
 4x1 struct array with fields:
     name
     date
     bytes
     isdir
 >> d.date
 ans =
 07-Oct-2008 10:17:11
 ------------------------------
 - R2007a
 ------------------------------
 >> d = dir
 d = 
 4x1 struct array with fields:
     name
     date
     bytes
     isdir
     datenum
 >> d.date
 ans =
 07-Oct-2008 10:32:00
 ------------------------------
 - R2007b, R2008a, R2008b
 ------------------------------
 >> d = dir
 d = 
 4x1 struct array with fields:
     name
     date
     bytes
     isdir
     datenum
 >> d.date
 ans =
 07-Okt-2008 10:32:00
 ------------------------------

Best Answer

Related Solutions

MATLAB: Does DATESTR return an error when parsing date strings with non-US local time/date formats in MATLAB 7.5 (R2007b)

MATLAB: Does DATENUM give me an error message when I pass German date strings as input arguments in MATLAB

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