RegExp pattern to extract date
===

I am using this pattern to extract confirmation dates from a text file and converting them to a date object (see my post here [Extract/convert date from string in MS Access][1]).

The current pattern matches all strings that look like a date, but may not be the confirmation date (which is always preceded by Confirmed by), and moreover, may not have complete date information (*e.g.* no AM or PM)

     Pattern: (\d+\/\d+/\d+\s+\d+:\d+:\d+\s+\w+|\d+-\w+-\d+\s+\d+:\d+:\d+)

Sample text: WHEN COMPARED WITH RESULT OF 7/13/12 09:06:42  NO SIGNIFICANT 
CHANGE; Confirmed by SMITH, MD, JOHN (2242) on 7/14/2012 3:46:21 PM;

The above pattern matches the following:

WHEN COMPARED WITH RESULT OF **7/13/12 09:06:42  NO** SIGNIFICANT CHANGE; 
Confirmed by SMITH, MD, JOHN (2242) on **7/14/2012 3:46:21 PM**;

I want the pattern to look for the date in the segment of the text file that begins with Confirmed by and ends with a semi-colon. Also, in order to properly convert the time, the pattern should match only AM or PM at the end. How can I restrict the pattern to this segment and add the additional AM or PM criteria?

Can anyone help?

  [1]: http://stackoverflow.com/questions/10392009/extract-convert-date-from-string-in-ms-access