Why do "datenum" and "datestr" not give the same date after conversion?

I am using the "datenum" function to create an object and get the date as a string using "datestr". I pass "20101231" (31-Dec-2010) as input to "datenum" but get back "31-Jan-2010" from "datestr" instead.

Following code shows how I am using the functions.

>> a = datenum('20101231','YYYYMMDD');
>> b = datestr(a)

b =

    '31-Jan-2010 00:12:00'

Answer 1

[MathWorks Support Team]

The issue happens because "MM" is the format for 'minute' in "datenum".

You can use the lower case "mm" to get the expected output:

>> a = datenum('20101231','YYYYmmDD');
>> b = datestr(a)

b =

    '31-Dec-2010'

To avoid the future confusion, we highly recommend using "datetime" with more intuitive letter identifiers, for example

>> a = datetime('2010-12-31')

a = 

  datetime

   31-Dec-2010

>> a = datetime('2010-12-31','InputFormat','yyyy-MM-dd')

a = 

  datetime

   31-Dec-2010