Core Function Pack

print pack("A*A*", $one, $two);

my $vec = pack("A*", "Hello");
printr $vec;
printr unpack("A*", $vec, 3);
# Prints
# {BINARY:5}
# {
#         [0] => 72
#         [1] => 101
#         [2] => 108
#         [3] => 108
#         [4] => 111
# }
# Hello

my $vec = pack("A*", "Hello");
my $chars = unpack("A/A/A2", $vec, 3);
print( "First letter: " . $chars[0] . "\n" );
print( "Second letter: " . $chars[1] . "\n" );
print( "Third and forth letter: " . $chars[2] . "\n" );
# Prints
# First letter: H
# Second letter: e
# Third and forth letter: ll

// Make an array of people
my $People = array(array("Name", "ID", "Birth", "Sex", "Race"));
push($People, array("Mike", 0, "1980", "M", "German"));
push($People, array("Tommy", 1, "1985", "M", "French"));
push($People, array("David", 2, "1950", "M", "Jewish"));
push($People, array("Sukara", 3, "1990", "F", "Japanese"));
push($People, array("Mary-Kate", 4, "1987", "F", "American"));
 
// Print them all in a nice formatted way
foreach($People as $Person)
{
	my List ( $Name, $ID, $Birth, $Sex, $Race ) = $Person;
	my $Sorted = pack("A12 A4 A7 A5 A*", $Name, $ID, $Birth, $Sex, $Race);
	echo "$Sorted\n";
}
# Prints
# Name        ID  Birth  Sex  Race
# Mike        0   1980   M    German
# Tommy       1   1985   M    French
# David       2   1950   M    Jewish
# Sukara      3   1990   F    Japanese
# Mary-Kate   4   1987   F    American

# Lets imagine this variable was loaded from a file
# It contains information that is using specific spaces
# to keep it organized so it can be displayed on the
# company computers properly
# We are going to read this information and process it
# You could use regexp or splitting but they would be
# impractical so lets use Unpack() instead
my $data = 
"
Date      |Description                | Income|Expenditure
01/24/2001 Zed's Camel Emporium                    1147.99
01/28/2001 Flea spray                              24.99
01/29/2001 Camel rides to tourists      235.00
01/29/2001 Tourist camel feedings       100.10
";
 
my $TotalIncome = 0.0;
my $TotalExpenditure = 0.0;
foreach(Lines($data) as $line)
{
	if(isEmptyOrNull(trim($line)))
		continue; # Skip useless entries
	my List( $date, $desc, $income, $expend  ) = unpack("A10/x/A27/x/A7/A*", $line);
	$income = trim($income); # Trim it so we can do arithmetics on it
	$expend = trim($expend); # Trim it so we can do arithmetics on it
	$TotalIncome += $income;
	$TotalExpenditure += $expend;
	# Print it just so prove we are reading it correctly other than that
	# it is pointless
	echo "Log: '$date' | '$desc' | '$income' | '$expend'\n";
}
echo "Total income is: $TotalIncome\n";
echo "Total expenditure is: $TotalExpenditure\n";
# Prints:
# Log: 'Date' | 'Description' | 'Income' | '|Expenditure'
# Log: '01/24/2001' | 'Zed's Camel Emporium' | '' | '1147.99'
# Log: '01/28/2001' | 'Flea spray' | '' | '24.99'
# Log: '01/29/2001' | 'Camel rides to tourists' | '235.00' | ''
# Log: '01/29/2001' | 'Tourist camel feedings' | '100.10' | ''
# Total income is: 335.1
# Total expenditure is: 1172.98

$binarydata = "\x04\x00\xa0\x00";
$array = Unpack("cchars/nint", $binarydata);
// The resulting array will contain the entries
// "chars" with value 4 and "int" with 160. 
printr $array;
// Prints:
// ARRAY
// {
//         [chars] => 4
//         [int] => 194
// }

$binarydata = "\x04\x00\xa0\x00";
$array = Unpack("c2chars/nint", $binarydata);
// The resulting array will contain the entries
// "chars1", "chars2" and "int". 
printr $array;
// Prints:
// ARRAY
// {
//         [chars1] => 4
//         [chars2] => 0
//         [int] => 49824
// }

$binarydata = Pack("nvc*", 0x1234, 0x5678, 65, 66);
// The resulting binary string will be 6 bytes long
// and contain the byte sequence 0x12, 0x34, 0x78, 0x56, 0x41, 0x42. 
printr $binarydata;
// Prints:
// {BINARY:6}
// {
//         [0] => 18
//         [1] => 52
//         [2] => 120
//         [3] => 86
//         [4] => 65
//         [5] => 66
// }

printr pack("C*",80,72,80);

function H2Str( $hex ) 
{
	return pack('H*', $hex);
}
 
function Str2H( $str )
{
	return unpack('H*', $str, true);
}
$txt = 'This is test';
$hex = Str2H( $txt );
$str = H2Str( $hex );
echo "${txt} => ${hex} => ${str}\n";

echo join (unpack('C*', 'abcdef'), ' ');
// 97 98 99 100 101 102

echo join (unpack('U*', 'こんにちは'), ' ');
// 33251 58259 37762 33251 58283 41345 33251

$arr = BinaryFromStr("Hello World!");
foreach ($arr as $i)
{
	println($i);
}
$str = Unpack("A*", $arr, true);
println($str);

$arr = Pack("d", 777.42);
foreach ($arr as $i)
{
	println($i);
}
$str = Unpack("d", $arr, 3);
println($str);

$arr = Pack("i", (int)777);
foreach ($arr as $i)
{
	println($i);
}
$str = Unpack("i", $arr, 3);
printr($str);

$str = "Hello World!";
println("Original String: " . $str);
$hex = Unpack("H*", $str, true);
println("Hex String: " . $hex);
$strf = Pack("H*", $hex);
println("Normal String: " . $strf);

Function StrToHex ( $Str )  
{
	$Str = unpack('H*', $Str, 3);
	# Operationally convert the hex characters
	# to upper case
	$Str =~ tr/a-z/A-Z/;
	return $Str;
}
Function HexToStr ( $Hex )
{
	$Hex =~ s/([\dA-Fa-f][\dA-Fa-f])/pack("C", dec($1))/eg;
	return $Hex;
}
my $Hex = StrToHex("Hello world!");
echo "Hex: $Hex\n";
my $Str = HexToStr($Hex);
echo "Str: $Str\n";