Perl Language Lista de valores verdaderos y falsos


Ejemplo

use feature qw( say );

# Numbers are true if they're not equal to 0.
say 0             ? 'true' : 'false'; # false
say 1             ? 'true' : 'false'; # true
say 2             ? 'true' : 'false'; # true
say -1            ? 'true' : 'false'; # true
say 1-1           ? 'true' : 'false'; # false
say 0e7           ? 'true' : 'false'; # false
say -0.00         ? 'true' : 'false'; # false

# Strings are true if they're not empty.
say 'a'           ? 'true' : 'false'; # true
say 'false'       ? 'true' : 'false'; # true
say ''            ? 'true' : 'false'; # false

# Even if a string would be treated as 0 in numeric context, it's true if nonempty.
# The only exception is the string "0", which is false.
# To force numeric context add 0 to the string
say '0'           ? 'true' : 'false'; # false
say '0.0'         ? 'true' : 'false'; # true
say '0e0'         ? 'true' : 'false'; # true
say '0 but true'  ? 'true' : 'false'; # true
say '0 whargarbl' ? 'true' : 'false'; # true
say 0+'0 argarbl' ? 'true' : 'false'; # false

# Things that become numbers in scalar context are treated as numbers.
my @c = ();
my @d = (0);
say @c            ? 'true' : 'false'; # false
say @d            ? 'true' : 'false'; # true

# Anything undefined is false.
say undef         ? 'true' : 'false'; # false

# References are always true, even if they point at something false
my @c = ();
my $d = 0;
say \@c            ? 'true' : 'false'; # true
say \$d            ? 'true' : 'false'; # true
say \0             ? 'true' : 'false'; # true
say \''            ? 'true' : 'false'; # true