{ 
    my $s = ''; 
    substr( $s, 1, 1, 'fred' ); 
    print $s; 
};;
substr outside of string at (eval 16) line 1, <STDIN> line 8.

{ 
    my $s = '  '; 
    substr( $s, 1, 1, 'fred' ); 
    print $s; 
};;
 fred