Python non-greedy regexes

Question

How do I make a python regex like        such that  given  a  b  c  d  e  python matches  b  instead of  b  c  d    I know that I can use        instead of      but I m looking for a more general solution that keeps my regex a little cleaner  Is there any way to tell python  hey  match this as soon as possible

User · Answer

Would not           work  That is the non-greedy syntax

User · Answer

gt  gt  gt  x    a  b  c  d  e   gt  gt  gt  re search r          x  group     b  c  d    gt  gt  gt  re search r           x  group     b     According to the docs      The           and     qualifiers are all greedy  they match as much text as possible  Sometimes this behavior isn   t desired  if the RE  lt    gt  is matched against   lt H1 gt title lt  H1 gt    it will match the entire string  and not just   lt H1 gt    Adding     after the qualifier makes it perform the match in non-greedy or minimal fashion  as few characters as possible will be matched  Using     in the previous expression will match only   lt H1 gt

User · Answer

Do you want it to match   b     Do as Zitrax and Paolo have suggested   Do you want it to match  b    Do   gt  gt  gt  x    a  b  c  d  e   gt  gt  gt  re search r             x  group 1   b

User · Answer

Using an ungreedy match is a good start  but I d also suggest that you reconsider any use of    -- what about this   groups   re search r             x

User · Answer

To start with  I do not suggest using     in regexes  Yes  I know  it is the most used multi-character delimiter  but it is nevertheless a bad idea  This is because  while it does match any amount of repetition for that character   any  includes 0  which is usually something you want to throw a syntax error for  not accept  Instead  I suggest using the   sign  which matches any repetition of length   1  What s more  from what I can see  you are dealing with fixed-length parenthesized expressions  As a result  you can probably use the  x  y  syntax to specifically specify the desired length   However  if you really do need non-greedy repetition  I suggest consulting the all-powerful    This  when placed after at the end of any regex repetition specifier  will force that part of the regex to find the least amount of text possible   That being said  I would be very careful with the   as it  like the Sonic Screwdriver in Dr  Who  has a tendency to do  how should I put it   slightly  undesired things if not carefully calibrated  For example  to use your example input  it would identify   1   note the lack of a second rparen  as a match

User · Answer

You seek the all-powerful     From the docs  Greedy versus Non-Greedy     the non-greedy qualifiers             or  m n         match as little   text as possible

User · Answer

As the others have said using the   modifier on the   quantifier will solve your immediate problem  but be careful  you are starting to stray into areas where regexes stop working and you need a parser instead   For instance  the string   foo  bar   baz  will cause you problems

[python] Python non-greedy regexes

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