#! /usr/bin/perl -lw
use strict ;


my %r = ( 'a' => 1, 'b' => 2, 'c' => 3) ;

my $keys = keys(%r) ;
print "keys = $keys" ;

printf "keys=%d\n", keys(%r) ;

##</code><code>##

keys = 3
Argument "c" isn't numeric in printf at ./t12.pl line 12.
keys=0

##</code><code>##

printf "keys=%d\n", (my $sc = keys(%r)) ;