Pass array and scalar to a Perl subroutine [duplicate]
You need to pass it in as a reference: calc(\@array, $scalar) And then access it as: my @array = @{$_[0]};
perl
How do I read two items at a time in a Perl foreach loop?
I believe the proper way to do this is to use natatime, from List::MoreUtils: from the docs: natatime BLOCK LIST Creates an array iterator, for looping over an array in chunks of $n items at a time. (n at a time, get it?). An example is probably a better explanation than I could give in … Read more
What does “0 but true” mean in Perl?
It’s normal behaviour of the language. Quoting the perlsyn manpage: The number 0, the strings ‘0’ and “”, the empty list (), and undef are all false in a boolean context. All other values are true. Negation of a true value by ! or not returns a special false value. When evaluated as a string … Read more
How to compile a Perl script to a Windows executable with Strawberry Perl?
Install PAR::Packer from CPAN (it is free) and use pp utility.
Can only ‘perl6’ parse Perl 6?
There is no perl6, and there are many Perl 6 compilers. Perl 6 has a grammar, although it’s written in Perl 6, so as long as you can understand that, it tells you everything you need to know. I just asked Larry this question, since I’m sitting across from him at lunch at the São … Read more
What’s the use of in Perl?
The answers above are all correct, but it might come across more plainly if you understand general UNIX command line usage. It is very common to want a command to work on multiple files. E.g. ls -l *.c The command line shell (bash et al) turns this into: ls -l a.c b.c c.c … in … Read more
How can I print source line number in Perl?
The __LINE__ literal is documented in the Special Literals section of the perldata man page. print “File: “, __FILE__, ” Line: “, __LINE__, “\n”; or warn(“foo”);
Javascript regex compared to Perl regex
From ECMAScript 2018 onwards, many of JavaScript’s regex deficiencies have been fixed. It now supports lookbehind assertions, even unbounded ones. Unicode property escapes have been added. There finally is a DOTALL (/s) flag. What is still missing: JavaScript doesn’t have a way to prevent backtracking by making matches final (using possessive quantifiers ++/*+/?+ or atomic … Read more
Most efficient way to check if $string starts with $needle in perl
rindex $string, $substring, 0 searches for $substring in $string at position <=0 which is only possible if $substring is a prefix of $string. Example: > rindex “abc”, “a”, 0 0 > rindex “abc”, “b”, 0 -1
Perl: Use s/ (replace) and return new string [duplicate]
require 5.013002; # or better: use Syntax::Construct qw(/r); print “bla: “, $myvar =~ s/a/b/r, “\n”; See perl5132delta: The substitution operator now supports a /r option that copies the input variable, carries out the substitution on the copy and returns the result. The original remains unmodified. my $old = ‘cat’; my $new = $old =~ s/cat/dog/r; … Read more