datenum problem in matlab

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Niki-Kuriaki Tsaprazi
Hi,
I have a problem in a Matlab code. I import dates from excel, then Matlab "reads" them with datestr, but after that, when Matlab convert them to numbers with datenum I have problem. The format of dates are 01/01/2012. When a day of a date is from 13 of a month till the end of the month Matlab read the day as 06/03/0021 or 06/04/0034. From 1st of a motnh till 12 of the month a have no problem because it convert the days to numbers correct..
When I run the code without importing dates from excel, I put them manually on editor I don't have any problem..
Please help me!

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采纳的回答

Pedro Villena
Pedro Villena 2012-11-7
编辑：Pedro Villena 2012-11-7
str = '01/01/2012'; %%string of the date, read from XLS file
First, you have to specify the date format that you have in your XLS file ( Control Panel >> Regional Configuration ).
format = 'dd/mm/yyyy';
or
format = 'mm/dd/yyyy';
Then, you could convert the date to number, and the number to date, without mistakes
str = '01/01/2012'; %%string of the date, read from XLS file
n = datenum(str,format);
s = datestr(n,format); %%s must be the equal to str

更多回答（2 个）

Titus Edelhofer
Titus Edelhofer 2012-11-7
Hi,
my guess is that your data is of the form dd/mm/yyyy, so first the day, then month, then year. But if you omit the date format when calling datenum, datenum guesses your data to be of American format (month first, so mm/dd/yyyy). That's why the first 12 will work (but give again guessing a wrong number!). To make the long story short, use the specific date format string as Pedro suggested.
Titus
Niki-Kuriaki Tsaprazi
Pedro and Titus, thank you very much for your answers. You help me a lot!! Now, my matlab file works correctly. Thank you very much!

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