Why do we use question mark literal in Python regular expression?

The question mark literal is used in different ways in Python Regular Expressions

Special character '?'

As a special character '?' causes the resulting RE to match 0 or 1 repetitions of the preceding RE. ab? will match either ‘a’ or ‘ab’

The question mark literal '?' is used following ways as per Python docs.

Making the quantifier non-greedy

*?, +?, ??

The '*', '+', and '?' qualifiers are all greedy; they match as much text as possible. Sometimes this behaviour isn’t desired; if the RE <.*> is matched against '<a> b <c>', it will match the entire string, and not just '<a>'. Adding ? after the qualifier makes it perform the match in non-greedy or minimal fashion; as few characters as possible will be matched. Using the RE <.*?> will match only '<a>'.

Rajendra Dharmkar

Published on 11-Jan-2018 07:06:53

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