Problem with ampersand and regex

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

Replies are listed 'Best First'.
Re: Problem with ampersand and regex by roboticus (Chancellor) on Dec 19, 2012 at 19:48 UTC
Try: `my $line = 'mail: asdf@123.com';` ...roboticus When your only tool is a hammer, all problems look like your thumb.	[reply] [d/l]
Re: Problem with ampersand and regex by toolic (Bishop) on Dec 19, 2012 at 19:50 UTC
Tip #1 from the Basic debugging checklist: use warnings (Possible unintended interpolation of @123). Use single quotes to avoid interpolation: `my $line = 'mail: asdf@123.com';` [download]	[reply] [d/l]
Re: Problem with ampersand and regex by davido (Cardinal) on Dec 19, 2012 at 19:51 UTC
`use warnings;`: "Possible unintended interpolation of @123..." Use single quotes: `my $line = 'mail: asdf@123.com';` and see if that clears it up for you. `use strict;` doesn't catch this one because it treats "digit" variables special, and allows them without declaration. Dave	[reply] [d/l] [select]
Re^2: Problem with ampersand and regex by Anonymous Monk on Dec 19, 2012 at 20:21 UTC
It looks like it trying to make the question overly simple, I made the mistake of omitting something very important. The definition of $line is coming from looping through an array as in the following: `foreach my $line (@array) { . . . }` [download] With that in mind, how can I define $line with single quotes? Sorry for the mistake.	[reply] [d/l]
Re^3: Problem with ampersand and regex by davido (Cardinal) on Dec 19, 2012 at 20:24 UTC
How are you filling `@array`? Dave	[reply] [d/l]
Re^4: Problem with ampersand and regex by Anonymous Monk on Dec 19, 2012 at 20:30 UTC
Re^5: Problem with ampersand and regex by frozenwithjoy (Priest) on Dec 19, 2012 at 21:18 UTC
Re: Problem with ampersand and regex by frozenwithjoy (Priest) on Dec 19, 2012 at 20:39 UTC
Others have already answered your question, but I just wanted to point out something related to the title of your post since it could potentially cause confusion. An ampersand is '&' (the Perl sigil for subroutine), whereas '@' is called at sign, at symbol, apetail, commercial at, or even ampersat.	[reply]
Re^2: Problem with ampersand and regex by Anonymous Monk on Dec 19, 2012 at 20:46 UTC
You are correct and thank you for pointing that out. Unfortunately, I am still having problems though. In an attempt to make the post easy to read, I left out some of the code and that makes the answer thus far impossible as far as I can see. Here is how my code should have looked: `foreach my $line (@array) { if ($line =~ /mail: /) { my $mail = substr($line, $+[$#+] ); print "mail=$mail\n"; } }` [download] With that, I see no way to use the single quotes as suggested. Any other possible solutions?? Thank you again.	[reply] [d/l]
Re^3: Problem with ampersand and regex by davido (Cardinal) on Dec 19, 2012 at 21:11 UTC
What do you get if you capture? `if( $line =~ /^mail:\s+([\S]+)$/ ) { my $mail = $1; print "mail=$mail\n"; }` [download] Dave	[reply] [d/l]
Re^4: Problem with ampersand and regex by Anonymous Monk on Dec 19, 2012 at 21:23 UTC
Re^5: Problem with ampersand and regex by davido (Cardinal) on Dec 19, 2012 at 21:48 UTC
Some notes below your chosen depth have not been shown here
Re^3: Problem with ampersand and regex by roboticus (Chancellor) on Dec 19, 2012 at 22:25 UTC
The '@' isn't a problem when you read it from a file. Only if you're using it in a double-quoted string. For example: `$ cat t.pl #!/usr/bin/perl use strict; use warnings; my @array = <DATA>; foreach my $line (@array) { if ($line =~ /mail: /) { my $mail = substr($line, $+[$#+] ); print "mail=$mail\n"; } } __DATA__ This @ should be just fine mail: this @ should also be fine $ perl t.pl mail=this @ should also be fine` [download] ...roboticus When your only tool is a hammer, all problems look like your thumb.	[reply] [d/l]
Re: Problem with ampersand and regex by ikegami (Patriarch) on Dec 19, 2012 at 23:24 UTC
Always use `use strict; use warnings;`! `my $line = "mail: asdf@123.com";` [download] should be `my $line = 'mail: asdf@123.com';` [download] Then you can simply use `if (my ($mail) = $line =~ /mail: (.*)/) { print "mail=$mail\n"; }` [download]	[reply] [d/l] [select]


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