regexp question

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

hi fellow monks !

an easy one. how do I make my regexp test if a given string starts with a constant followed by a '/' (slash) and more characters, or no slash and no more characters. I think this will make it clearer:

my $path = '/tmp/foo';

$ex1 = '\tmp\foo\bar';   # is OK
$ex2 = '\tmp\foo';       # is OK    
$ex3 = '\tmp\foo\';      # is OK
$ex4 = '\tmp\food';      # is NOT OK
[download]

anyone?

Hotshot

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Re: regexp question by FoxtrotUniform (Prior) on Feb 11, 2002 at 17:58 UTC
Untested, but should get the idea across. `my $path =~ /^\Q$str\E # the base string; '\tmp\foo', e.g. (\\.)? # optionally match a slash, etc. $ # match end of string /x;` [download] Insisting on matching `$` at the end of the regex prevents you from matching "extra" chars that don't start with a backslash. Update:* Yes, do escape the base string. (Regex updated.) Thanks Sweeper! `-- :wq`	[reply] [d/l]
Re x 2: regexp question by Sweeper (Pilgrim) on Feb 12, 2002 at 06:20 UTC
I have not tested either, but I think you should escape special characters in `$string`: my $path =~ /^\Q$string\E # the base string; '\tmp\foo', e.g. (\\.*)? # optionally match a slash, etc. $ # match end of string /x;	[reply]
Re: regexp question by hawson (Monk) on Feb 12, 2002 at 02:04 UTC
Try this pattern: `/^$path(?=(\/[\S\/]\|$))/` It says, more or less: match the contents of `$path`, but only if followed by a slash (and optionally more slashes and non-space characters), or the end of the line. Here's my test program `#!/usr/bin/perl -w my $path='/tmp/foo'; my @ex=('/tmp/foo', '/tmp/foo/', '/tmp/foo/bar', '/baz/tmp/foo/', '/tm +p/food'); print join(" ", grep( /^$path(?=(\/[\w\/]\|$))/, @ex)), "\n";` [download]	[reply] [d/l] [select]