Question

I have the following regex from regex lib that does a fine job to catch some PO Box variations. The only thing it does not do is to match trailing digits:

PO Box 123

Can anyone please help modifying this regex to also match trailing digits?

\b[P|p]?(OST|ost)?\.?\s*[O|o|0]?(ffice|FFICE)?\.?\s*[B|b][O|o|0]?[X|x]?\.?\s+[#]?(\d+)\b

Thanks.

Answer 1

Assuming the trailing digits in “PO Box 123” are “123”, the regex does match them. It even captures the number to backreference 3.

There are a large number of flaws in your regex. For instance, it matches OST|||| 0.

Might I suggest my own P.O. Box regex?

^(?:Post (?:Office )?|P[. ]?O\.? )?Box #?([0-9]+)

Enable the option to make ^ and $ match at line breaks (usually, /m), and enable the case insensitive option (usually, /i). Don’t enable the free-spacing option (usually, /x).

Here are some examples of strings it matches:

• Post Office Box #123
• post box 123
• P.O. box 123
• P O Box 123
• Po. box 123
• PO Box 123
• Box 123

The trailing numbers are captured to backreference 1.