%% in perl mean

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

Hello Monks

what is the meaning of "%%" in perl

I couldnt get any clue on it

Here's the code

if( QLearn('LEARN') )
        {       $var->{SPEC} =~ s/%%/$var->{LEARN}{TEST}/ ;        }
[download]

what is the meaning of the above statement badly in need of help

Thank in advance for the help

Comment on %% in perl mean Download Code

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Re: %% in perl mean by tobyink (Canon) on Sep 11, 2013 at 20:34 UTC
In this case, it's just two percent character which are being searched for in a search-and-replace operation (`s///`). However it does have two special meanings in Perl... The `printf` and `sprintf` functions take a formatting string as their first argument. This formatting string uses special codes that start with a "%" character; such as "%d" which is a placeholder for an integer. When you want the output to include a literal "%" character, you can't just place that as-is in the formatting string; instead you use "%%". The other place "%%" is special in Perl is that there's a global hash called `%%`. You can assign values to it and use it like any other hash; the only difference is that you don't declare it with `my` or `our` - it's pre-defined. `use Data::Dumper; %% = (foo => 1, bar => 2); print Dumper \%%;` [download] `use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name`	[reply] [d/l] [select]
Re: %% in perl mean by keszler (Priest) on Sep 11, 2013 at 16:59 UTC
Binding Operators and Regexp Quote Like Operators If the string in $var->{SPEC} contains the characters "%%", the first occurance of "%%" will be changed to whatever string is in the variable $var->{LEARN}{TEST}. (Assuming that `if( QLearn('LEARN') )` is true.)	[reply] [d/l]
Re: %% in perl mean by SuicideJunkie (Vicar) on Sep 11, 2013 at 17:04 UTC
That's just some '%' characters to search for. Perhaps what you really want to know is what the s/// part is all about.	[reply]
Search and replace by Laurent_R (Canon) on Sep 11, 2013 at 17:26 UTC
Just look what it does: `DB<10> $string = 'foo%%bar'; DB<11> $string =~ s/%%/BAZ/; DB<12> print $string fooBAZbar DB<13>` [download]	[reply] [d/l]
Re: %% in perl mean by Jim (Curate) on Sep 11, 2013 at 22:27 UTC
This appears to be a snippet from an ad hoc template processing Perl script. Is it? If so, then the pairs of percent symbols (`%%`) are likely tags in the template that are matched and replaced with variable text; specifically, the value referred to by the hash variable `$var->{LEARN}{TEST}`.	[reply] [d/l] [select]
Re: %% in perl mean by Anonymous Monk on Sep 11, 2013 at 23:24 UTC
This is probably just a means-nothing token that is meant to be put into a template-string of some kind to mark the place where (in this very statement) a substitution is to be performed. Look at the content of this element of "$var" and see if, as I suspect, it contains that particular substring at a fortuitous place.	[reply]
Re: %% in perl mean by Anonymous Monk on Sep 11, 2013 at 22:25 UTC
You can also use ppi_dumper or Re: ppiwx / wxPPI / wxppixregexp xPPIx_Regexp_linecol_onize / PPIx::Regexp::Element::column_number to walk the code and see what each part is (operator....), before looking it up in the docs	[reply]