A scalar value is interpreted as TRUE in the Boolean sense if it is not
       the null string or the number 0 (or its string equivalent, "0").  The
       Boolean context is just a special kind of scalar context where no
       conversion to a string or a number is ever performed.

##</code><code>##

Truth and Falsehood
 
       The number 0, the strings '0' and '', the empty list "()", and "undef"
       are all false in a boolean context. All other values are true.
       Negation of a true value by "!" or "not" returns a special false value.
       When evaluated as a string it is treated as '', but as a number, it is
       treated as 0.