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The length()
function is used to determine the number of characters in an expression, such as a string or a scalar variable.
To determine the number of characters in an expression use the length()
function:
#!/usr/bin/perl use strict; use warnings; my $name = 'Bob'; my $size = length($name); print "$size\n"; exit 0;
This example prints the number of characters in the string $name
:
3
The Perl scalar()
function forces an array into scalar context, giving you the length:
#!/usr/bin/perl use strict; use warnings; my @planets = qw(mercury venus earth mars jupiter); my $size = scalar(@planets); print "$size\n"; exit 0;
This example shows us the number of elements in the array @planents
:
5
Sometimes you will also want to know the number of elements in a hash. This is easily done using the keys()
function to return the keys as an list, and the scalar()
function to return how many keys there are:
#!/usr/bin/perl use strict; use warnings; my %planet_mass_compared_to_earth = ( mercury => 0.055, venus => 0.86, earth => 1.0, mars => 0.11, jupiter => 318, ); my $size = scalar(keys %planet_mass_compared_to_earth); print "$size\n"; exit 0;
The output of this program is:
5
Determining length and size perldoc -f length perldoc -f scalar perldoc bytes