#!/usr/bin/perl

my $hexstr = "0xb400189"; 

# Convert to a number in machine-byte order
my $num = hex $hexstr;

# Convert to a number in big-endian order
my $be_num = pack("N",$num);

# Extract the 4 bytes
my($a,$b,$c,$d) = unpack("C4",$be_num);

# And print!
printf "%x.%x.%x.%x\n",$a,$b,$c,$d;

##</code><code>##

printf "%x.%x.%x.%x\n", unpack("C4",pack("N",hex $hexstr));