CODEWITHSUNDEEP
linuxperlhexdecimal
Dem
Dem

Reputation: 53

Linux Perl - Convertion of Hex Value to Decimal

I am developing a script that convert collected HEX ( I don't know the Bit format of them) values to Decimal Values.

One of the example is the hex value: fef306da If I convert it, I receive 4277339866.

Website where I found the expected value (Decimal from signed 2's complement:): https://www.rapidtables.com/convert/number/hex-to-decimal.html

Do you guys have a solution how can I convert hex fef306da to decimal -17627430. Note: I get wrong value conversion when I convert hex that have (-)negative sign when decimal.

Thanks all!

Upvotes: 2

Views: 873

Answers (4)

ikegami
ikegami

Reputation: 385546

You could use pack

my $hex = "fef306da";
my $num = hex($hex);
$num = unpack("l", pack("L", $num));
say $num;  # -17627430

or

my $hex = "fef306da";
$hex = substr("00000000$hex", -8);   # Pad to 8 chars
my $num = unpack("l>", pack("H8", $hex));
say $num;  # -17627430

But simple arithmetic will do.

my $hex = "fef306da";
my $num = hex($hex);
$num -= 0x1_0000_0000 if $num >= 0x8000_0000;
say $num;  # -17627430

Upvotes: 1

Polar Bear
Polar Bear

Reputation: 6798

If you interested in binary conversion then check following code (fef306da is 32bit number)

use strict;
use warnings;
use feature 'say';

my $input   = 'fef306da';
my $hex     = hex($input);
my $dec;

if( $hex & 0x80000000 ) {
   $dec = -1 * ((~$hex & 0x7fffffff)+1);
} else {
   $dec = $data;
}

say $dec;

Output

-17627430

Tip: Two's complement

Upvotes: 1

Bruce
Bruce

Reputation: 1542

Look at pack and use modifiers for unsigned and signed values.

my $hex_value = "fef306da";
my $output_num = unpack('l', pack('L', hex($hex_value)));
print $output_num; ## -17627430

Perform a test on each hex value to determine if it is a 16bit or 32bit value. Then use the correct modifier with pack for long or short values.

Upvotes: 3

Mike
Mike

Reputation: 1375

it seems that you expect your decimal to be 32bit signed integer, but HEX($n) returns a 64bit one so you may try repack it

perl -e 'print unpack "l", pack "L", hex( "fef306da" )'

Upvotes: 3

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