The answer here does depend a little bit on what you mean by 'empty'. The earlier answers only tell you if an array has any elements, but not tell you what they contain.
If by empty you mean 'only contains defined elements' then you will need the following test instead:
my @a = (0,1,2,3);
foreach (@a) {print "'$_'\n";} # Prints each element.
print "\@a exists\n" if @a;
print "\@a is not Empty\n" if grep {defined($_)} @a;
# Prints '@a is not empty' if any element in '@a' is defined.
my @b = (1, undef)
foreach (@b) {print "'$_'\n";}
print "\@b exists\n" if @b;
print "@b is not Empty\n" if grep {defined($_)} @b;
Of course, if you want to know if the array contains only true values, then you can get away without using the defined() bit.
Edited: Examples reworked by davido.
