Matlab Regular Expression for datetime string

Hi, I have string that contains time information. "this_file_05312016' here 05(month)31(day)2016(year) I am able to make it work for search January any day by using "01[01-31]+2016" Now I want to do search January - March, any day of 2016. I used [01-03][01-31]+2016 seems not working. What I might be missing? Thank you for your help.

[Azzi Abdelmalek]

The question is not clear

Answer 1

[Walter Roberson]

Least specific to dates:

0[1-3]\d\d2016

more specific:

0[1-3]([0-2][0-9]|3[01])2016

Even more specific:

(0[13]([0-2][0-9]|3[01])|02[0-2][0-9])2016

or more compactly,

(0[13]([0-2]\d|3[01])|02[0-2]\d)2016

extending the more specific to April or beyond would add more complexity. Extending the search to non-leapyears would add more complexity.

Often, the very first of those possibilities is good enough, if you already know that all the things that vaguely look like dates are going to be valid dates, and you are just concerned with selecting the right months. The more complex versions are suitable for the case where you might have mixed in other things that are not valid dates and you need to select only valid dates, such as if there was this_file_02302016 that you want to skip because of the invalid date, there never being a February 30th.

[Lili Xiao]

Thank you very much.