Basic regular expressions

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

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Re: Basic regular expressions by mjscott2702 (Pilgrim) on Oct 21, 2010 at 12:53 UTC
1. Is looking for at least 1 asterisk (the * is escaped here) 2. Is looking for a forward slash at the end of the $path string i.e. anchored by the $ 3. Correct, the . metacharacter is escaped, so remove .gz from the end of the string	[reply]
Re: Basic regular expressions by Corion (Patriarch) on Oct 21, 2010 at 12:55 UTC
No. In detail: No, see perlre on what the backslash does No, see perlre on what the backslash does Yes, also see perlre on what the backslash does	[reply]
Re: Basic regular expressions by toolic (Bishop) on Oct 21, 2010 at 13:18 UTC
In addition to reading the documentation that Corion mentioned, here is one tool that can help decipher regexes: YAPE::Regex::Explain. For example: use YAPE::Regex::Explain; print YAPE::Regex::Explain->new('\')->explain(); The regular expression: (?-imsx:\) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- \* '*' ---------------------------------------------------------------------- ) end of grouping ---------------------------------------------------------------------- [download]	[reply] [d/l]
Re: Basic regular expressions by muba (Priest) on Oct 21, 2010 at 12:55 UTC
1. This code is just looking for any number of backslashes `if ($var ~= m/\/)` [download] No, the backslash works as an escape character. You're matching for a literal "". 2. This code is matching for a backslash but what does the $ mean `unless($path ~= m/\/$/)` [download] No. The backslashs works as an escape character again. '$' means 'match at end of string' (you seem to know the meaning of $ in your next question, though). So this matches against a forward slash at the end of $path. 3. This code is replacing . gz at the end of a string. with nothing `$output ~= s/\.gz$//;` [download] Correct. You're welcome.	[reply] [d/l] [select]
Re: Basic regular expressions by Ratazong (Monsignor) on Oct 21, 2010 at 13:54 UTC
For this topic there is also a great collection by planetscape: My favourite regex tools. It also includes a link to an online regex-explainer HTH, Rata	[reply]
Re: Basic regular expressions by raybies (Chaplain) on Oct 21, 2010 at 14:28 UTC
1. if you want to look for AT LEAST one \ in your code the simplest regex would be... `if ($var =~ /\\/)` 2. this example actually is looking at a forward slash. The dollar ($) symbol is the end of a line or string, so it would be any single slash at the end of a string. 3. is correct. oh and follow the advice of the folks here, and read perlre...	[reply] [d/l]