Your code and Randal's code only works if you believe a foobar is an integer ;-)

C:\>type test.pl
foreach (1.2, foobar){
     print &is_int ($_)?"$_ is an integer\n":"$_ is not an integer\n";
  }

sub is_int{
  my $testvar =shift;
  use integer;
  my $intval=$testvar_*1;
  no integer;
  return $testvar == $intval;
}

C:\>perl test.pl
1.2 is not an integer
foobar is an integer

C:\>

C:\>type test.pl
$_ = 'foobar';
print "'$_' is an integer" if is_int($_);

sub is_int {
  $_[0] == int $_[0];
}

C:\>perl test.pl
'foobar' is an integer
C:\>
[download]

Sadly this is not the only problem. You might also try testing foo2you and foo2.1
 
tachyon