Perl lc Function
last modified April 4, 2025
The Perl lc function converts strings to lowercase. It handles
ASCII characters by default and follows Unicode rules when appropriate.
lc is locale-aware and works with international characters.
It returns a new string rather than modifying the original variable.
Basic lc Usage
The simplest way to use lc is on a single string variable.
#!/usr/bin/perl use strict; use warnings; use v5.34.0; my $text = "Hello World!"; my $lower = lc($text); print "Original: '$text'\n"; print "Lowercase: '$lower'\n";
We demonstrate lc converting a mixed-case string to lowercase.
The original string remains unchanged.
$ ./basic.pl Original: 'Hello World!' Lowercase: 'hello world!'
Comparing Strings Case-Insensitively
lc is useful for case-insensitive string comparisons.
#!/usr/bin/perl
use strict;
use warnings;
use v5.34.0;
my $input = "YeS";
my $match = "yes";
if (lc($input) eq lc($match)) {
print "Input matches (case-insensitive)\n";
} else {
print "Input doesn't match\n";
}
This script compares user input case-insensitively by converting both strings to lowercase before comparison.
$ ./compare.pl Input matches (case-insensitive)
Processing Arrays
lc can process array elements using map.
#!/usr/bin/perl
use strict;
use warnings;
use v5.34.0;
my @words = ("APPLE", "Banana", "CherRY");
my @lower_words = map { lc } @words;
print "Original: @words\n";
print "Lowercase: @lower_words\n";
We convert all elements of an array to lowercase. The original array remains unchanged while we create a new lowercase version.
$ ./array.pl Original: APPLE Banana CherRY Lowercase: apple banana cherry
International Characters
lc handles international characters correctly.
#!/usr/bin/perl use strict; use warnings; use v5.34.0; use utf8; my $text = "ÉLÉGANT Zürich"; my $lower = lc($text); binmode STDOUT, ':utf8'; print "Original: '$text'\n"; print "Lowercase: '$lower'\n";
This demonstrates lc working with accented characters and
umlauts. Note the use utf8 pragma for Unicode support.
$ ./unicode.pl Original: 'ÉLÉGANT Zürich' Lowercase: 'élégant zürich'
lc vs lcfirst
lc differs from lcfirst which only affects the
first character.
#!/usr/bin/perl use strict; use warnings; use v5.34.0; my $text = "Perl Programming"; print "lc: ", lc($text), "\n"; print "lcfirst: ", lcfirst($text), "\n";
lc converts the entire string while lcfirst only
changes the first character to lowercase.
$ ./compare_functions.pl lc: perl programming lcfirst: perl Programming
Using with Hashes
lc can normalize hash keys for case-insensitive lookups.
#!/usr/bin/perl
use strict;
use warnings;
use v5.34.0;
my %colors = (
red => "#FF0000",
green => "#00FF00",
blue => "#0000FF"
);
my $user_input = "RED";
my $color_code = $colors{lc $user_input};
if (defined $color_code) {
print "Hex code for $user_input is $color_code\n";
} else {
print "Color not found\n";
}
We use lc to normalize user input before hash lookup. This
allows case-insensitive access to hash values.
$ ./hash.pl Hex code for RED is #FF0000
Locale Awareness
lc respects the current locale settings for case conversion.
#!/usr/bin/perl use strict; use warnings; use v5.34.0; use locale; my $text = "İSTANBUL"; setlocale(LC_ALL, 'tr_TR.UTF-8'); print "Turkish locale: ", lc($text), "\n"; setlocale(LC_ALL, 'en_US.UTF-8'); print "English locale: ", lc($text), "\n";
This shows how locale affects lowercase conversion, particularly with Turkish dotted/dotless I. Note: Locale must be available on your system.
$ ./locale.pl Turkish locale: i̇stanbul English locale: i̇stanbul
Best Practices
- Use for normalization: Standardize strings before comparison.
- Combine with chomp: Clean input with both functions.
- Consider Unicode: Ensure proper encoding for non-ASCII.
- Performance: Avoid unnecessary conversions in loops.
Source
This tutorial covered Perl's lc function with practical
examples demonstrating its usage in various scenarios.
Author
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