Mathew Snyder schreef:
> Dr.Ruud:
>> flotsan:
>>> it is told the following two statements are
>>> different:
>>>
>>> 1) if ($_ = <STDIN>) { print; } # suboptimal: doesn't test defined
>>> 2) if (defined($_ = <STDIN>)) { print; } # best
>>>
>>> But as I see it, these two do the same thing
>>
>> perl -le '
>> print defined($_) ? "\"$_\"" : "<undefined>"
>> , "\tis "
>> , $_ ? "true" : "false"
>> for undef, "", 0, "0", 0E0, "0E0", 0.0, "0.0", 1
>> '
>
> That's over my head...
Just play with it then. This is equivalent:
#!/usr/bin/perl
use warnings ;
use strict ;
local $\ = "\n" ;
my @test = (undef, '', 0, '0', 0E0, '0E0', 0.0, '0.0', (), \(),
\undef, 1) ;
for (@test)
{
print defined($_) ? "'$_'" : '<undefined>'
, "\tis "
, $_ ? 'true' : 'false' ;
}
--
Affijn, Ruud
"Gewoon is een tijger."
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