Question

Perl automatically initializes variables to undef by default.

Is there a way to override this default behavior and tell the Perl interpreter to initialize variables to zero (or some other fixed value)?

Answer 1

The recommendation in Code Complete is important for language such as C because when you have

int f(void) {
   int counter;
}

the value of counter is whatever happens to occupy that memory.

In Perl, when you declare a variable using

my $counter;

there is no doubt that the value of $counter is undef not some random garbage.

Therefore, the motivation behind the recommendation, i.e. to ensure that all variables start out with known values, is automatically satisfied in Perl and it is not necessary to do anything.

What you do with counters is to increment or decrement them. The result of:

my $counter;
# ...
++ $counter;

is well defined in Perl. $counter will hold the value 1.

Finally, I would argue that, in most cases, counters are not necessary in Perl and code making extensive use of counter variables may need to be rewritten.