Why does !1 give me nothing in Perl?

Question

This is strange. The following:

$sum = !0;
print $sum;

prints out 1 as you would expect. But this

$sum = !1;
print $sum;
         


        

Answer 1

The ! operator does boolean operations. "" (The empty string) is just as false as 0 is. 1 is a convenient true value. ! shouldn't be relied on to do anything other than produce some true/false value. Relying on the exact value beyond that is dangerous and may change between versions of Perl.