perldoc perlvar is the first place to check for any special-named Perl variable info. Quoting: @_: Within a subroutine the array @_ contains the parameters passed to that subroutine. More details can be found in perldoc perlsub (Perl subroutines) linked from the perlvar: Any arguments passed in show up in the array @_ . Therefore, … Read more
In terms of speed: #1 and #4, but not by much in most instances. You could write a benchmark to confirm, but I suspect you’ll find #1 and #4 to be slightly faster because the iteration work is done in C instead of Perl, and no needless copying of the array elements occurs. ($_ is … Read more
For starters, use strict; (and to a lesser extent, use warnings;) helps find typos in variable names. Even experienced programmers make such errors. A common case is forgetting to rename an instance of a variable when cleaning up or refactoring code. Using use strict; use warnings; catches many errors sooner than they would be caught … Read more
For string comparisons in Perl, use eq or ne: if ($str eq “”) { // … } The == and != operators are numeric comparison operators. They will attempt to convert both operands to integers before comparing them. See the perlop man page for more information.
Since you need to match content without including it in the result (must match name=” but it’s not part of the desired result) some form of zero-width matching or group capturing is required. This can be done easily with the following tools: Perl With Perl you could use the n option to loop line by … Read more
Strawberry Perl uses CPAN, which means that you are up to date as far as modules are concerned. When things are added to CPAN, you have immediate access to them. Strawberry Perl also comes with MinGW which means that Strawberry Perl can use quite a few XS modules directly from CPAN without any modification. The … Read more
The rule of thumb is to use the function most suited to your needs. If you just want the keys and do not plan to ever read any of the values, use keys(): foreach my $key (keys %hash) { … } If you just want the values, use values(): foreach my $val (values %hash) { … Read more
Prototypes aren’t bad if used correctly. The difficulty is that Perl’s prototypes don’t work the way people often expect them to. People with a background in other programming languages tend to expect prototypes to provide a mechanism for checking that function calls are correct: that is, that they have the right number and type of … Read more
Try setting PERL_MM_USE_DEFAULT like so: PERL_MM_USE_DEFAULT=1 perl -MCPAN -e ‘install My::Module’ It should make CPAN answer the default to all prompts.
Test whether something exists at given path using the -e file-test operator. print “$base_path exists!\n” if -e $base_path; However, this test is probably broader than you intend. The code above will generate output if a plain file exists at that path, but it will also fire for a directory, a named pipe, a symlink, or … Read more