in reply to integer container for float

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";
}

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Cheers,
Rob

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Re^2: integer container for float
by BrowserUk (Patriarch) on Mar 28, 2016 at 14:08 UTC

    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

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    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

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