How many days to learn Perl?

Determining how many days it takes to learn Perl depends heavily on your background, the depth of knowledge you want to achieve, and how you define “learning Perl.” Perl’s tagline, TMTOWTDI (“There’s More Than One Way To Do It”), highlights its flexibility but also means learning can be broad and varied.

Here’s a rough guideline to help you estimate the time needed:

• Basic Syntax and Core Concepts (3-7 days): Understanding Perl’s variables ($ for scalars, @ for arrays, % for hashes), control structures, regex basics, and built-in functions can be done relatively quickly, especially if you know other programming languages.
• Intermediate Features (2-4 weeks): Learning context (scalar vs list), references, complex data structures, modules, regular expressions in depth, and file I/O usually takes more time. This phase opens up more idiomatic Perl usage.
• Advanced Topics (varies): Mastering Perl’s object-oriented programming, advanced regex features, XS modules (for C extensions), in-depth CPAN modules, and writing robust, maintainable Perl code happens over months or years.

Perl’s powerful text processing and expressive syntax mean it can be learned incrementally. You can write small useful programs within hours, while mastery is an ongoing journey.

Common Learning Tips

• Practice reading and writing Perl scripts daily.
• Use core Perl documentation with perldoc, especially perlintro and perlre.
• Experiment with different Perl idioms to leverage TMTOWTDI without getting overwhelmed.
• Write lots of regexes, since they’re central to Perl.

Perl Code Example: Calculate Days from Now

Here’s a simple Perl script that calculates the number of days from today until a future date you input. This example uses core Perl features like scalar variables, date calculations, and prints output. It demonstrates Perl's straightforward syntax and date arithmetic using built-in functions only (no external modules).

use strict;
use warnings;

print "Enter a future date (YYYY-MM-DD): ";
chomp(my $input = <STDIN>);

# Parse the input date
if ($input =~ /^(\d{4})-(\d{2})-(\d{2})$/) {
    my ($year, $month, $day) = ($1, $2, $3);

    # Convert input date to epoch seconds (simple calculation)
    # Note: This naive approach assumes no timezones/time changes for simplicity
    my $future_epoch = timegm(0,0,0,$day,$month-1,$year-1900);
    my $now_epoch    = time();

    my $seconds_diff = $future_epoch - $now_epoch;
    if ($seconds_diff <= 0) {
        print "The date you entered is not in the future.\n";
    } else {
        my $days = int($seconds_diff / (60 * 60 * 24));
        print "There are $days day" . ($days != 1 ? 's' : '') . " until $input.\n";
    }
} else {
    print "Invalid date format. Use YYYY-MM-DD.\n";
}

# timegm is in core module Time::Local from Perl 5 onwards
use Time::Local qw(timegm);

This script demonstrates Perl’s use of sigils ($ for scalars), pattern matching with regexes, and using core modules. By practicing with simple yet practical examples like this, you can build your Perl skills steadily.

In summary, you can learn the basics of Perl in less than a week if you focus daily, but becoming comfortable with Perl’s unique idioms, powerful regex, and ecosystem typically takes weeks to months. Thankfully, Perl’s flexibility allows you to start creating working scripts almost immediately and improves with practice.