Source code in the perl programming language

my $size1 = -s 'input.txt';
my $size2 = -s '/input.txt';


use File::Spec::Functions qw(catfile rootdir);
my $size1 = -s 'input.txt';
my $size2 = -s catfile rootdir, 'input.txt';


my $size1 = (stat 'input.txt')[7];  # builtin stat() returns an array with file size at index 7
my $size2 = (stat '/input.txt')[7];