[Brisbane-pm] Still Struggling With Regex Syntax

[David Bussenschutt]

Martin,
How about this:
 
# this example contains numbers, whitespace and other irrelevant stuff, possibly newlines
my $rain = "   345678        xxx\nblah";  
 
#magic:
$rain =~ s/^.*?(\d+).*$/$1/s; 
 
# my explanation: 
# the basic substitution operator looks like this: s///; but with extra characters between the slashes as required below....
# ^.*? means match anything, starting from the start of the string (non-greedy, so it doesn't ever match a number)
# (\d+) means match any continual section of numbers, and the brackets means remember them as $1
# .*$ means match anything, finishing at the end string
# the $1 means "replace the entire matched string with just the bit remembered in $1" (ie the numbers).
# the 's' at the end means don't treat newlines as special ( http://perldoc.perl.org/perlre.html )
 
#NOTE: this code gives you left-most string of consecutive numbers in any string.  eg if $rain started as 'xxx1234yyy5678' it would end up as just '1234'
 
print $rain;  # prints the string '345678'
 
 

-----Original Message-----
From: brisbane-pm-bounces+david.bussenschutt=qmtechnologies.com at pm.org [mailto:brisbane-pm-bounces+david.bussenschutt=qmtechnologies.com at pm.org]On Behalf Of Martin Jacobs
Sent: Monday, 16 April 2007 2:34 PM
To: Brisbane Perl Group
Subject: [Brisbane-pm] Still Struggling With Regex Syntax


Hi folks,

I still don't get it (quite).

The story so far...

I have split my rainfall record, and the right-most scalar is $rain.

I now want to make sure that $rain holds a numeric value, without any whitespace, newlines or other nasties.

If I try

$rain = ($rain =~ m|\d+\.?\d*|);

It returns 1, which, presumably, is the number of times it gets a match.

What's the right syntax for saying 'make $rain contain the numeric values in $rain"?



Regards,
Martin
Visit my website...
 <http://web.mac.com/martin_jacobs1> http://web.mac.com/martin_jacobs1 





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