How to I convert a string to a number (ASCII to Integer)

#How to I convert a string to a number

use strict;

use warnings;

sub atoi {

    # Initialize to 0 to avoid "uninitialized value" warnings

    my $t = 0; 

    

    # Process each character of the first argument

    foreach my $d (split(//, shift())) {

        $t = $t * 10 + $d;

        # Optional: Comment out the next line if you don't want to print intermediate steps

        # print "$t\n"; 

    }

    return $t;

}

# Declare $number with 'my' to comply with 'use strict'

my $number = atoi("123");

print "string '123' number value is $number\n";