Regexp Help

[cptk]

string = "id <xx> MM blah blah"

'MM' is a optional value in string ...

If 'MM' exist, I want to capture contents seperately both before and after 'MM'. If 'MM' doesn't exist, just capture the entire string.

examples:
If 'MM' exist ...

/(.*)M{2}(.*)/
$1 = 'id <xx> '
$2 = ' blah blah'
This is ok...but obviously I have to account if 'MM' is not in string.

I've tried ...

/(.*)M{0,2}(.*)/
/(.*(?=MM))M{0,2}(.*)/

Can someone enlighten me and stop my head banging ...?
Thanks ...





/

 

[cptk]

/([^M]*)(M+)?(.*)/

I think this works ... but needs tightening up ...

Like
/([^M{2}]*)(M{2})?(.*)/

 

[chazoid]

you could do something like this unless speed is important. Using $` and $' tend to slow things down.

# $` returns everything before the matched string. $'  returns everything after the matched string.

$string = "id <xx> MM blah blah";

if ($string =~ /\bMM\b/ ) {
   $before = $`;
   $after  = $';
}
else {
    # do something else
}
print "$before\n$after";

And don't be afraid to break up regexs into a few simpler ones if they get too complicated. You'll spend less time coding, and other people will have an easier time understanding them.

 

[prex1]

And if we stopped using regexes where they are not useful?
This will be much faster (and simpler to understand):

my($start,$end)=split/MM/,$string;

If there is no 'MM' [tt]$end[/tt] will be [tt]undef[/tt] and [tt]$start[/tt] will be the same as [tt]$string[/tt].

Franco

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[chazoid]

split() doesn't use regular expressions?

 

[cptk]

Thanks guys for the responses ...

I was just trying to exclude a repeating char class,
something like this:

string: 'ABC 123 MM'

/([M]{2})+/ ## returns 'MM'

but something like this doesn't work:
/([^M]{2})+/ ## expecting 'ABC 123 '