Hi sm@sh,

I don't know much about the internals, but from what I do know I'd guess it might be looking at the POK/IOK flags:

$ perl -MDevel::Peek -e 'Dump(1); Dump("1")';
SV = IV(0x21490e8) at 0x21490f8
  REFCNT = 1
  FLAGS = (IOK,READONLY,PROTECT,pIOK)
  IV = 1
SV = PV(0x2129fa0) at 0x2149168
  REFCNT = 1
  FLAGS = (POK,IsCOW,READONLY,PROTECT,pPOK)
  PV = 0x218fef0 "1"\0
  CUR = 1
  LEN = 10
  COW_REFCNT = 0
$ perl -MDevel::Peek -e '$a=42; $a="Hello"; Dump($a)';
SV = PVIV(0x83d2e0) at 0x8321f0
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  IV = 42
  PV = 0x834920 "Hello"\0
  CUR = 5
  LEN = 10
  COW_REFCNT = 1

[download]

However, the much bigger question on my mind is why you need to know this? Perl "casts" between strings and numbers transparently, except for the case where a string can't be converted to a number, which you can determine beforehand with Scalar::Util's looks_like_number. Are you writing code that needs to peek behind the curtains more than that?

Regards,
-- Hauke D

In reply to Re: How can I test for the representation of an integer? by haukex
in thread How can I test for the representation of an integer? by sm@sh

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