Re: methods for dealing with zero '0' as a string or char

> am I an idiot or is this a common issue that I should be handling differently?

No you are not an idiot, it's just that different people have different understandings about a true scalar.

This means you need to be explicit what you exactly want to test.

if (defined($string)) tells me that I didn't get undef
if(length($string)) is testing against empty strings (NB: not the same like undef !!!)
if($scalar) is testing against Perl's concept of truthiness.

Background: Perl is designed such that scalars are transparent to their C type, i.e. no matter if the 0 is internally an integer, float or string. °

Hence the inner representation of a scalar can change without effecting the boolean context.

NB: If you really need an explicit string type which is only false when empty, you are free to create your own "string" object and overload it's bool behaviour.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice}

update

°) in other languages with explicit types you are forced to transform a number inside a string into an int or float before using numeric operations.

For instance in Python

a + b can be a string concat or a numeric addition depending on the type, in Perl it's always only an addition.
and 3/2 will yield 1 because it's an integer operation.

Comment on Re: methods for dealing with zero '0' as a string or char Select or Download Code

Replies are listed 'Best First'.
Re^2: methods for dealing with zero '0' as a string or char by kcott (Archbishop) on Aug 16, 2019 at 07:40 UTC
Just as an adjunct to what you have there, length returns `FALSE` for a zero-length `EXPR` and also an undefined `EXPR`. The latter behaviour was introduced in `5.12.0` (perl5120delta: Other potentially incompatible changes). Interestingly, given the general discussion here, the `FALSE` value returned for a zero-length `EXPR` is `0`, while the `FALSE` value returned for an undefined `EXPR` is `undef`. — Ken	[reply] [d/l] [select]
Re^3: methods for dealing with zero '0' as a string or char by LanX (Saint) on Aug 16, 2019 at 13:08 UTC
for clarification > Interestingly, given the general discussion here, the FALSE value returned for a zero-length EXPR is 0, while the FALSE value returned for an undefined EXPR is undef. Some operators in Perl return an internal magic boolean value, which is !!0 for FALSE and !!1 for TRUE. `length` is not one of them, it returns values which are interpreted as FALSE or TRUE, returning undef for undef is very consistent in my eyes. Though one probably could argue that `warnings` `uninitialized` should trow a warning here, I'm a bit confused in this matter. I remember that tobyink started a discussion once that `warnings` `uninitialized` leads to inconsistent behaviour. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply] [d/l] [select]