Hello All,

Why is a NV and IV created in this case as opposed to just an IV? If instead $scalar2 is set to '0', only an IV is created.

Additionally, why is NV used to track numeric value for $scalar1 when it is modified and not IV? If $scalar2 is instead set to '0' initially, numeric value will be stored in IV.

Thanks for any enlightenment you can offer.

use Devel::Peek;

my $scalar1 = '';
Dump($scalar1);
my $temp1 = $scalar1+1;
Dump($scalar1);
$scalar1 = $scalar1+1;
Dump($scalar1);

SV = PV(0x36974) at 0x43ef74
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x2b23ad4 ""\0
  CUR = 0
  LEN = 4
Argument "" isn't numeric in addition (+) at C:\Projects\test.pl line 
+17.
SV = PVNV(0x2bbc254) at 0x43ef74
  REFCNT = 1
  FLAGS = (PADMY,POK,pIOK,pNOK,pPOK)
  IV = 0
  NV = 0
  PV = 0x2b23ad4 ""\0
  CUR = 0
  LEN = 4
SV = PVNV(0x2bbc254) at 0x43ef74
  REFCNT = 1
  FLAGS = (PADMY,NOK,pNOK)
  IV = 0
  NV = 1
  PV = 0x2b23ad4 ""\0
  CUR = 0
  LEN = 4

###

my $scalar2 = '0';
Dump($scalar2);
my $temp2 = $scalar2+1;
Dump($scalar2);
$scalar2 = $scalar2+1;
Dump($scalar2);

SV = PV(0xa26974) at 0x2965d3c
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x2aa9cd4 "0"\0
  CUR = 1
  LEN = 4
SV = PVIV(0x43297c) at 0x2965d3c
  REFCNT = 1
  FLAGS = (PADMY,IOK,POK,pIOK,pPOK)
  IV = 0
  PV = 0x2aa9cd4 "0"\0
  CUR = 1
  LEN = 4
SV = PVIV(0x43297c) at 0x2965d3c
  REFCNT = 1
  FLAGS = (PADMY,IOK,pIOK)
  IV = 1
  PV = 0x2aa9cd4 "0"\0
  CUR = 1
  LEN = 4

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In reply to What is the distinction between IV and NV variables? by Kc12349

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