add double quotes to a perl variable

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

I have a scrit that picks out any word with a "$" in it. I am attempting to add double quotes to this variable in perl

#!/usr/bin/perl
use warnings; 
use strict; 
my $escaping_file = $ARGV[0];
open( my $filehandle, "<" , "$escaping_file" ) || die "failed : $!";
while (<$filehandle>) {
    if ($_ =~ /^\$?\w+\$+\w+\$?$/g) {
    s/\$/\\\$/g ;
    #$escaped_wquotes = "".$_."" ;
    #$escaped_wquotes = "\"$_\"" ;
    $escaped_wquotes = qq("$_") ;
    print "$escaped_wquotes";
    }
}
[download]

each time I try i get this. the two commented out varaibles give the saem result.

[casper@casperbox$ ./check_escapes /tmp/new_list
"bc\$stp
""soc\$ny
""icon\$test
""btec\$stp
""ec\$stp2
""bos\$nyc
""tec\$live5
""\$foo\$foo\$
""\$foo\$baz
""foo\$bad\$
[download]

i am trying to get the varaible to spit this out.

"bc\$stp"
"soc\$ny"
"icon\$test"
"btec\$stp"
"ec\$stp2"
"bos\$nyc"
"tec\$live5"
"\$foo\$foo\$"
"\$foo\$baz"
"foo\$bad\$"
[download]

Comment on add double quotes to a perl variable Select or Download Code

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Re: add double quotes to a perl variable by Kenosis (Priest) on Nov 15, 2013 at 20:33 UTC
Add `chomp`: `while (<$filehandle>) { chomp; ... print "$escaped_wquotes\n";` [download] (Also, consider changing `\|\| die` to `or die` -- it's a precedence issue...)	[reply] [d/l] [select]
Re^2: add double quotes to a perl variable by casperdaghost (Initiate) on Nov 15, 2013 at 20:40 UTC
ok so there was a new line at the end of each interation of while. while adds a new line after each print?	[reply]
Re^3: add double quotes to a perl variable by Kenosis (Priest) on Nov 15, 2013 at 20:49 UTC
An input record separator (found in Perl's variable `$/` and usually set to `\n`) determines the end of a line ('record') when reading from a file--like you were doing in your `while` loop. It's kept on the end of the line, unless you do something like `chomp`ing the line. In your case, not removing the input record separator produced undesirable results in your final output. (Sometimes, however, the very last line of a file may not terminate with an input record separator, because the line ends at the end of the file.)	[reply] [d/l] [select]
Re: add double quotes to a perl variable by oiskuu (Hermit) on Nov 16, 2013 at 07:02 UTC
Note that escaping only `'$'` may lead to problems in a general case. For example, a string such as `'abc\$xyz'` converts to `'abc\\$xyz'`, where the `'$'` remains unprotected. I would suggest using `quotemeta()`, as your strings are just labels anyway: `#! /usr/bin/perl -l while (<>) { chomp; print '"'.quotemeta.'"' if /^[\$\w]+$/; }` [download] Or simply: `#! /usr/bin/perl -ln print '"'.quotemeta.'"' if /^[\$\w]+$/;` [download]	[reply] [d/l] [select]
Re^2: add double quotes to a perl variable by tobyink (Canon) on Nov 16, 2013 at 18:57 UTC
Consider also `B::perlstring()`, which not only handles escaping, but also adds the quote characters... `#!/usr/bin/perl -l use B; while (<>) { chomp; print B::perlstring($_) if /^[\$\w]+$/; }` [download] The B module is bundled with Perl itself, so you already have it. The `perlstring()` function was added in Perl 5.8, so this will not work on Perl 5.6. `use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name`	[reply] [d/l] [select]