$val = chr(someFunction());

if($val == " ")
{
    #do something

}
elsif($val == 0)
{
   #do something else
}

if ($val eq " ") ...

if (looks_like_a_number($val) and $val == 0) {
    #do something
}

if ($val eq 0) {
    #do something
}

if ($val ~~ 0) {
    #do something
}

use strict;
use warnings;

my $val = chr(someFunction());

if($val == " ")
{
    #do something

}
elsif($val == 0)
{
   #do something else
}

sub someFunction {
    return 1;
}

(W numeric) The indicated string was fed as an argument to an operator
   that expected a numeric value instead.  If you're fortunate the message
   will identify which operator was so unfortunate.