Extracting consecutive digits using regexp

I expected

regexp('ITEM 123', '.+(\d+)', 'tokens')

to return '123'. Why does it only return '3'? What would be the correct expression?

Answer 1

[per isakson]

These two returns "123"

%%
cac = regexp('ITEM 123', '.+?(\d+)', 'tokens' )
%%
cac = regexp('ITEM 123', '[^\d]+(\d+)', 'tokens' )

First, '.+' matches anything up til the end of the text, next it gives back just as little as needed to match '(\d+)' , which is one digit.

'.+?' matches as little as needed so that '(\d+)' is able to match the following text.

I prefer '[^\d]+(\d+)'

Or why not just

cac = regexp('ITEM 123', '\d+', 'match' )

[Hau Kit Yong]

Many thanks! For the first expression, what does the '?' character do? I've only seen it in lookaround operations, but always in the form of '?=', '?<=' etc. and never by itself.

[per isakson]

Search Quantifiers and Lazy on the page Regular Expressions