regexp problem

jeanluca has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks, I've a problem with a string I need to parse. Here are a few examples of this string:

$str = " abc defgh ij klmnop " ; # case 1
$str = " abc defgh ij klmnop qrst uvwxyz" ; # case 2
$str = "abc defgh ij" ; #case 3
[download]

I need the text + the spaces in between but not the spaces at the beginning or end!!
I tried to find a regexp for this, this one almost works:

($str) = ($str =~ /^\s([\w+\s{0,}]{1,})\s{0,}$/) ; #case 2/3
[download]

It only fails in case 1, it leaves a space at the end....
Any suggestions how to fix this expression ?

Thanks in advance
Luca

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Re: regexp problem by Limbic~Region (Chancellor) on Dec 08, 2005 at 13:38 UTC
jeanluca, Perhaps I am being dense but it sounds like what you want to do is remove leading and trailing whitespaces. This is a FAQ IIRC. In any case - the following should do the trick: `$str =~ s/^\s+\|\s+$//g;` [download] Cheers - L~R	[reply] [d/l]
Re: regexp problem by secret (Beadle) on Dec 08, 2005 at 13:36 UTC
maybe you can trim the spaces at the ends first ? `s/^\s+//, s/\s+$// for $string;` [download]	[reply] [d/l]
Re: regexp problem by ysth (Canon) on Dec 08, 2005 at 13:39 UTC
`($str) = ($str =~ /^\s(.?)\s*\z/)` or just `$str =~ s/^\s+//; $str =~ s/\s+\z//;` [download]	[reply] [d/l] [select]
Re: regexp problem by SamCG (Hermit) on Dec 08, 2005 at 15:29 UTC
from perlfaq: `for ($string) { s/^\s+//; s/\s+$//; }` [download]	[reply] [d/l]
Re: regexp problem by Perl Mouse (Chaplain) on Dec 08, 2005 at 14:12 UTC
If you may assume the string contains at least two non-space characters, I'd write: `/(\S.\S)/` [download] which will match the first non-space character, the last non-space character, and everything in between. If you may not make the assumption, I'd modify it slightly: `/(?=\S)(.\S)/` [download] If you know the non-space characters will be letters (or digits or underscores), you can also write: `/(\b.+\b)/` [download] which also works for strings containing just a single letter. `Perl --((8:>*`	[reply] [d/l] [select]