Output of perldoc -q round Does Perl have a round() function? What about ceil() and floor()? Trig functions? Remember that int() merely truncates toward 0. For rounding to a certain number of digits, sprintf() or printf() is usually the easiest route. printf(“%.3f”, 3.1415926535); # prints 3.142 The POSIX module (part of the standard Perl distribution) … Read more
See perldoc perlop. Use lt, gt, eq, ne, and cmp as appropriate for string comparisons: Binary eq returns true if the left argument is stringwise equal to the right argument. Binary ne returns true if the left argument is stringwise not equal to the right argument. Binary cmp returns -1, 0, or 1 depending on … Read more
This is the idiom I’ve always used to get a modified copy of a string without changing the original: (my $newstring = $oldstring) =~ s/foo/bar/g; In perl 5.14.0 or later, you can use the new /r non-destructive substitution modifier: my $newstring = $oldstring =~ s/foo/bar/gr; NOTE: The above solutions work without g too. They also … Read more
How does our differ from my and what does our do? In Summary: Available since Perl 5, my is a way to declare non-package variables, that are: private new non-global separate from any package, so that the variable cannot be accessed in the form of $package_name::variable. On the other hand, our variables are package variables, … Read more
We will look at how the contents of this array are constructed and can be manipulated to affect where the Perl interpreter will find the module files. Default @INC Perl interpreter is compiled with a specific @INC default value. To find out this value, run env -i perl -V command (env -i ignores the PERL5LIB … Read more
On Unix: usually you start cpan in your shell: $ cpan and type install Chocolate::Belgian or in short form: cpan Chocolate::Belgian On Windows: If you’re using ActivePerl on Windows, the PPM (Perl Package Manager) has much of the same functionality as CPAN.pm. Example: $ ppm ppm> search net-smtp ppm> install Net-SMTP-Multipart see How do I … Read more
You can use awk: awk ‘{ sum += $1 } END { print sum }’ file
In Perl, the following evaluate to false in conditionals: 0 ‘0’ undef ” # Empty scalar () # Empty list (”) The rest are true. There are no barewords for true or false.
exec executes a command and never returns. It’s like a return statement in a function. If the command is not found exec returns false. It never returns true, because if the command is found it never returns at all. There is also no point in returning STDOUT, STDERR or exit status of the command. You … Read more
The first and third ways are the same: they evaluate an array in scalar context. I would consider this to be the standard way to get an array’s size. The second way actually returns the last index of the array, which is not (usually) the same as the array size.