Re: integer container for float

[syphilis]

BrowserUk has nicely covered the case where $Config{ivsize} == 8.

Similarly it's possible to pack/unpack single precision floats when $Config{ivsize} == 4.
Obviously, you can't use the "Q" template because, according to the docs, that applies only to ivsize of 8. But you can use the "j" (or "J") templates with the "f" template:

#!perl -l
use strict;
use warnings;
use Config;


my $val = 3.625;

if($Config{ivsize} == 4) {

 my $to_int =  unpack 'j', pack 'f', $val;;
 print $to_int; # 1080557568

 my $to_float =  unpack 'f', pack 'j', $to_int;;
 print $to_float; # 3.625

}
else {
 print "Can't pack C floats to IV/UV";
}

Cheers,
Rob

[BrowserUk]

Indeed.

He could even use 2 x 32-bit ints as an intermediary for a double:

($lo, $hi) = unpack 'NN', pack 'd', 3.14159265358979;;

print $lo, $hi;;
288179284 4213246272

print unpack 'd', pack 'NN', 288179284, 4213246272;;
3.14159265358979

Or even 4 x 16-bit ints:

( $_0, $_1, $_2, $_3 ) = unpack 'n*', pack 'd', exp(1);;

print unpack 'd', pack 'n*', $_0, $_1, $_2, $_3;;
2.71828182845905