Empty string: Difference between revisions

=={{header|Perl}}==

In Perl, an empty string is often used to represent a false value.

<lang Perl>$s = "";

if ($s) { ... } # false

# to tell if a string is false because it's empty, or it's plain not there (undefined)

$s = undef;

if (defined $s) { ... } # false; would be true on ""

# though, perl implicitly converts between strings and numbers, so this is also false

$s = "0";

if ($s) { ... } # false; also false on "000", "0.0", "\x0", "0 with text", etc

# but a string that converts to number 0 is not always false, though:

$s = "0 but true";

if ($s) { ... } # it's true! black magic!</lang>