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

[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 ;

[BrowserUk]

The reason has nothing to do with pack or unpack, it is the same reason that printing a hex constant doesn't print exactly what you see.

print 0x428c0000;

1116471296

Perl automatically converts hex values (as indicated by 0x...) to it internal (binary) representation when parsing the source code. It becomes just another perl number.

Whenever perl prints out a number, it prints the ascii representation of it's decimal value, unless you specifically state that you want it printed in some other form. Ie. using printf or sprintf or similar.