Solved

How do I convert an int to byte array in PHP?

Posted on 2010-08-25
2
1,461 Views
Last Modified: 2012-05-10
I need to convert an integer value to a 2 byte array and then to a 2 character string to write to a text file.  I obtain the value from the file using:

$fhandle = fopen($this->FilePath, 'r');
$myVal  = unpack('S',fread($fhandle, 2));
echo 'My Val = '.$myVal[1]; //let's say that $myVal = 1234

How do I convert the value back to the original format from an integer?

Thank you,

j
0
Comment
Question by:j-tech
2 Comments
 
LVL 3

Accepted Solution

by:
Mathias earned 500 total points
ID: 33528511
Take a look at this:

Output:
----------
0x1234
LB: 0x34
HB: 0x12
0x1234
LB: 0x34
HB: 0x12
0x12345678LW: 0x5678
HW: 0x1234
0x12345678LW: 0x5678
HW: 0x1234
Start: 0x1234
Array: 0x34, 0x12,
Array: 52, 18
String: 4
Hex output
34 12                                           | 4.
----------
<?php
// Function found at: http://www.theserverpages.com/scripts/
// Please leave this comment intact when using this code!
function hexoutput($data, $width=16)
{
	$st=0;
	$txt="";
	$out="";
	for ($i=0; $i<strlen($data); $i++)
	{
		$n=ord(substr($data,$i,1));
		$c=str_pad(dechex($n),2,"0",STR_PAD_LEFT);
		$out.=$c." ";
		if ($n==32 || $n>32 && $n<127 || $n>160)
		{
			$txt.=substr($data,$i,1);
		}
		else
		{
			$txt.=".";
		}
		if ($i % $width == $width-1)
		{
			$out.="| ".$txt."\n";
			$txt="";
		}
	}
	$out.=str_repeat("   ",$width-($i % $width));
	$out.="| ".$txt;
	$out.="\n";
	return $out;
}

function LO_BYTE($x)
{
	return ($x & 0x00FF);
}
function HI_BYTE($x)
{
	return (($x & 0xFF00) >> 8);
}
function LO_WORD($x)
{
	return ($x & 0xFFFF);
}
function HI_WORD($x)
{
	return (($x >> 16) & 0xFFFF);
}
function MAKE_WORD($a, $b)
{
	return (($b << 8) + $a);
}
function MAKE_LONG($a, $b)
{
	return ($a | ($b << 16));
}

echo '<pre>';

$test = 0x1234;
echo sprintf("0x%04X\n", $test);

echo sprintf("LB: 0x%02X\n", LO_BYTE($test));
echo sprintf("HB: 0x%02X\n", HI_BYTE($test));

$test = MAKE_WORD(LO_BYTE($test), HI_BYTE($test));
echo sprintf("0x%04X\n", $test);

echo sprintf("LB: 0x%02X\n", LO_BYTE($test));
echo sprintf("HB: 0x%02X\n", HI_BYTE($test));

$test = 0x12345678;
echo sprintf("0x%08X", $test);

echo sprintf("LW: 0x%04X\n", LO_WORD($test));
echo sprintf("HW: 0x%04X\n", HI_WORD($test));

$test = MAKE_LONG(LO_WORD($test), HI_WORD($test));
echo sprintf("0x%04X", $test);

echo sprintf("LW: 0x%04X\n", LO_WORD($test));
echo sprintf("HW: 0x%04X\n", HI_WORD($test));

$test = 0x1234;
echo sprintf("Start: 0x%04X\n", $test);
echo "Array: ";
$arr = array(LO_BYTE($test), HI_BYTE($test));
foreach ($arr as $a)
	echo sprintf("0x%02X, ", $a);
echo "\n";
echo "Array: ".implode(", ", $arr)."\n";
echo "String: ";
$str = '';
foreach ($arr as $a)
{
	$str .= sprintf("%c", $a);
}
echo $str."\n";
echo "Hex output\n";
echo hexoutput($str);

echo '</pre>';
?>

Open in new window

0
 

Author Comment

by:j-tech
ID: 33533377
Thanks TDS, that worked perfectly.  Also helped with converting an integer to a single byte array to single character string.  Appreciate it!
0

Featured Post

Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Nothing in an HTTP request can be trusted, including HTTP headers and form data.  A form token is a tool that can be used to guard against request forgeries (CSRF).  This article shows an improved approach to form tokens, making it more difficult to…
This article discusses four methods for overlaying images in a container on a web page
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…
This tutorial will teach you the core code needed to finalize the addition of a watermark to your image. The viewer will use a small PHP class to learn and create a watermark.

840 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question