Regex doesn't match - what am I doing wrong?

[Sriram]

Hi,

I am having trouble matching a regex that combines a negated character
class and an anchor ($). Basically, I want to match all strings that
don't end in a digit. So I tried:

bash-2.05a@bermuda:1 5$perl -e 'while (<STDIN>) { if (/[^0-9]$/) {
print;}}'
skdsklds
skdsklds
sklskl2 <== why does this match? it ends in a digit.
sklskl2

This matched all strings regardless of whether or not they ended in a
digit. But the complemented regex seems to work fine:

bash-2.05a@bermuda:1 3$perl -e 'while (<STDIN>) { if (/[0-9]$/) {
print;}}'
sdkldsklds2
sdkldsklds2
sdsk2
sdsk2
sks <==== doesn't match as expected

I replaced [0-9] with [\d] but got the same results.

On the other hand, grep works as expected:

bash-2.05a@bermuda:9 $grep '[0-9]$'
sdksdjk2
sdksdjk2
22221
22221
sdjkdsjk <== doesn't match as expected

bash-2.05a@bermuda:1 1$grep '[^0-9]$'
sdklsdklds
sdklsdklds
sdkldslk2 <== doesn't match as expected

What am I doing wrong? Here's the perl version info:

bash-2.05a@bermuda:1 7$perl -V
Summary of my perl5 (revision 5.0 version 6 subversion 1)
configuration:
Platform:
osname=linux, osvers=2.4.17-0.13smp, archname=i386-linux
uname='linux daffy.perf.redh at.com 2.4.17-0.13smp #1 smp fri feb 1
10:30:48 est 2002 i686 unknown '
config_args='-des -Doptimize=-O2 -march=i386 -mcpu=i686 -Dcc=gcc
-Dcf_by=Red Hat, Inc. -Dcccdlflags=-fPIC -Dinstallprefix=/usr
-Dprefix=/usr -Darchname=i386-linux -
Dvendorprefix=/usr -Dsiteprefix=/usr -Uusethreads -Uuseithreads
-Uuselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Di_ndbm -Di_gdbm
-Di_shadow -Di_syslog -Dman3ext=3pm
'
hint=recommende d, useposix=true, d_sigaction=def ine
usethreads=unde f use5005threads= undef useithreads=und ef
usemultiplicity =undef
useperlio=undef d_sfio=undef uselargefiles=u ndef usesocks=undef
use64bitint=und ef use64bitall=und ef uselongdouble=u ndef
Compiler:
cc='gcc', ccflags ='-fno-strict-aliasing -I/usr/local/include',
optimize='-O2 -march=i386 -mcpu=i686',
cppflags='-fno-strict-aliasing -I/usr/local/include'
ccversion='', gccversion='2.9 6 20000731 (Red Hat Linux 7.2
2.96-109)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=defi ne, longlongsize=8, d_longdbl=defin e,
longdblsize=12
ivtype='long', ivsize=4, nvtype='double' , nvsize=8, Off_t='off_t',
lseeksize=4
alignbytes=4, usemymalloc=n, prototype=defin e
Linker and Libraries:
ld='gcc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -ldl -lm -lc -lcrypt -lutil
perllibs=-lnsl -ldl -lm -lc -lcrypt -lutil
libc=/lib/libc-2.2.5.so, so=so, useshrplib=fals e,
libperl=libperl .a
Dynamic Linking:
dlsrc=dl_dlopen .xs, dlext=so, d_dlsymun=undef ,
ccdlflags='-rdynamic'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'


Characteristics of this binary (from libperl):
Compile-time options:
Built under linux
Compiled at Apr 1 2002 12:23:22
@INC:
/usr/lib/perl5/5.6.1/i386-linux
/usr/lib/perl5/5.6.1
/usr/lib/perl5/site_perl/5.6.1/i386-linux
/usr/lib/perl5/site_perl/5.6.1
/usr/lib/perl5/site_perl/5.6.0
/usr/lib/perl5/site_perl
/usr/lib/perl5/vendor_perl/5.6.1/i386-linux
/usr/lib/perl5/vendor_perl/5.6.1
/usr/lib/perl5/vendor_perl

[Arno H.P. Reuser]

Re: Regex doesn't match - what am I doing wrong?

On Wed, 10 Mar 2004 14:47:40 -0800, Sriram wrote:

The string 'sklskl2' does not end in a digit, it ends in a character
return. That's probably why everything always matches. If you chop the $_
first, like

perl -e 'while (<stdin>){chop $_; if (/[^0-9]$/) {print } }'

results will look more promising.

Hope this helps.

[color=blue]
> Hi,
>
> I am having trouble matching a regex that combines a negated character
> class and an anchor ($). Basically, I want to match all strings that
> don't end in a digit. So I tried:
>
> bash-2.05a@bermuda:1 5$perl -e 'while (<STDIN>) { if (/[^0-9]$/) {
> print;}}'
> skdsklds
> skdsklds
> sklskl2 <== why does this match? it ends in a digit.
> sklskl2
>[/color]

[Sriram]

Re: Regex doesn't match - what am I doing wrong?

Hi,

Thanks! That works much better; so does '/[^0-9]\n/' or !/[0-9]$/.

My Perl book says "The $ and \Z assertions can match not only at the
end of the string, but also one character earlier than that, if the
last character of the string happens to be a newline." This is also
how I'm used to regexs working in grep/sed etc.

I'm baffled that $ behaves differently when used in conjunction with a
negated character class. The complemented regex /[0-9]$/ works without
chop. Why the subtle difference?

Sriram

"Arno H.P. Reuser" <bibliothecaris @xs4all.nl> wrote in message news:<pan.2004. 03.11.08.12.18. 223363@xs4all.n l>...[color=blue]
> On Wed, 10 Mar 2004 14:47:40 -0800, Sriram wrote:
>
> The string 'sklskl2' does not end in a digit, it ends in a character
> return. That's probably why everything always matches. If you chop the $_
> first, like
>
> perl -e 'while (<stdin>){chop $_; if (/[^0-9]$/) {print } }'
>
> results will look more promising.
>
> Hope this helps.
>
>[color=green]
> > Hi,
> >
> > I am having trouble matching a regex that combines a negated character
> > class and an anchor ($). Basically, I want to match all strings that
> > don't end in a digit. So I tried:
> >
> > bash-2.05a@bermuda:1 5$perl -e 'while (<STDIN>) { if (/[^0-9]$/) {
> > print;}}'
> > skdsklds
> > skdsklds
> > sklskl2 <== why does this match? it ends in a digit.
> > sklskl2
> >[/color][/color]