Revision as of 11:53, 3 October 2009 (view source) rosettacode>Glennj (add JavaScript) ← Older edit		Revision as of 13:11, 26 October 2009 (view source) Underscore (talk \| contribs) (→‎{{header\|Perl}}: Expanded.) Newer edit →
Line 183: =={{header\|Perl}}== The values in Perl that are false are: <tt>0</tt> (as a number (including <tt>0.0</tt>), or as the string <tt>'0'</tt>, but '''not''' the string <tt>"'0.0"'</tt>), the empty string <tt>""<nowiki>''</nowiki></tt>, the empty list <tt>()</tt>, and <tt>undef</tt>. Everything else is true. See [http://perldoc.perl.org/perlsyn.html#Truth-and-Falsehood perlsyn]. Objects may break these rules at will via [http://perldoc.perl.org/overload.html#*-_Boolean%2c-string-and-numeric-conversion_ overloading]. ~~Everything else is true.~~ Perl has no builtin "true" or "false" keywords. However, as a special case, literal <tt>1</tt>s and <tt>0</tt>s will never cause a "Useless use of a constant in void context" warning. Another special case worth pointing out here is that the string <tt>'0 but true'</tt> won't provoke a warning if it's used as a number. ~~Perl has no special "true" or "false" keywords.~~ ~~[http://perldoc.perl.org/perlsyn.html#Truth-and-Falsehood]~~ =={{header\|PHP}}==

Boolean values (view source)