Re: Converting Hex to Float (and vise versa) (overly simple)

[tye]

This should work on many platforms for the example data you gave:

my $float= unpack "f", pack "L", 0x428C0000;

(assuming the value you wanted was the nice-looking "70").

but I'm not sure how to reconcile the terms "in ASCII" vs. "e.g. 0x428C0000". Perhaps you have a string like "0x428C0000":

my $string= "0x428C0000";
my $float= unpack "f", pack "L", hex $string;

or perhaps you have a string of bytes whose hex values are 42, 8C, 00, and 00:

my $string= "\x42\x8C\x00\x00";

in which case you could pick between these two, depending on whether the source and destination systems are the same or different endian:

$float= unpack "f", $string;
$float= unpack "f", scalar reverse $string;

or you could use use two steps to auto-handle the receiving ends endianness (since your example data appears to show me the endianness of the source):

my $string= "\x42\x8C\x00\x00";
my $float= unpack "f", pack "L", unpack "N", $string;

[Anonymous Monk]

$float= unpack "f", pack "L", 0x428C0000;
print $float; # 70
$float= unpack "L", pack "f", 70 ;
print $float; # print 1116471296

Please tye, could you just point me why?

[BrowserUk]

Because

print hex '428C0000';
1116471296

The original input was in hex, you are printing decimal.

[Anonymous Monk]

Thanks, but the thing which hurt me is the 'no-symmetry':



$float= unpack "f", pack "L", 0x428C0000;
# $float is 70
$float= sprintf("%lx", unpack "L", pack "f", 70 );
print $float; # print 428C0000


I take this as a fact but I don't understand why the exact
opposite expression doesn't give back the original data:


$is_not_hex = unpack "L", pack "f", 70 ;