15
20
25

##</code><code>##

use Fcntl qw(:seek);

open(my $fh, '+<', 'foo');
seek($fh, 3, SEEK_SET);
print $fh '94';
close($fh);

##</code><code>##

$foo = "ab cd ef";
substr($foo, 3, 2) = "cat";
say $foo;