I'm trying to convert the number 101 to the binary \x00\x65 and I don't know how.
I've tried this:
$decimal = 101;
return bin2hex(pack('S', $decimal));
But the result is 6500.
The number is going to be changed and this has to be dynamical of course. Is there a way to convert it?
This has to be used to send data thru a socket (TCP/IP) using this code:
$socket = #fsockopen('127.0.01', '8810', $err_no, $err_str);
if(!$socket){
exit('Errore #'.$err_no.': '.$err_str);
}else{
fwrite($socket, "?B\x00\x65\x00\x01\x00\x01");
$read = fread($socket, 255);
return $read;
fclose($socket);
// $decimal = 101;
// return bin2hex(pack('n', $decimal));
}
See the fwrite string I'm sending.
Sending data in different ways doesn't work.
return bin2hex(pack('n', $decimal));
You simply have a problem with endianness. 'n' is for unsigned short (always 16 bit, big endian byte order).
Use following function
string decbin ( int $number )
This function will return binary number in string format. You need to pass decimal number as parameter.
For better explanation and more example just go though php official documentation
Related
Im trying to do a php multiplication of two 32bit long hexadecimal valuey with PHP and it seems it is messing up this calculation, the same happens if i multiplicate it as decimal value.
The calculation is as example:
0xB5365D09 * 0xDEBC252C
Converting to decimal before with hexdec doesnt change anything.
The expected result should be 0x9DAA52EA21664A8C but PHPs result is 0x9DAA52EA21664800
Example:
<?php
$res = 0xB5365D09 * 0xDEBC252C;
echo dechex(intval($res));
?>
What i am doing wrong here?
PHP8.2 running on debian, 64bit AMD.
So, for others to find the answer:
Someone stated in the comments to my question, that the result is above the PHP_MAX_INT limit. So when PHP handle it as a FLOAT, there will be some precision of the result lost. I got it to work using bcmath. In my case, i didnt do math with the result any further so i grabbed some piece of code from here, and made a simple function which does what i need. Here you can see a minimum-example:
function bcmul_hex($h1, $h2) {
$dec = bcmul($h1, $h2);
$hex = '';
do {
$last = bcmod($dec, 16);
$hex = dechex($last).$hex;
$dec = bcdiv(bcsub($dec, $last), 16);
} while($dec>0);
return $hex;
}
echo bcmul_hex(0xB5365D09, 0xDEBC252C);
Here is a live example.
If you're trying to perform a mathematical operation on a hexadecimal value in PHP, you can use the hexdec function to convert the hexadecimal value to a decimal value, perform the operation, and then use the dechex function to convert the result back to a hexadecimal value.
Here's an example:
<?php
$hex1 = "B5365D09";
$hex2 = "DEBC252C";
// Convert hexadecimal values to decimal
$dec1 = hexdec($hex1);
$dec2 = hexdec($hex2);
// Perform multiplication operation
$result = $dec1 * $dec2;
// Convert result back to hexadecimal
$hex_result = dechex($result);
// Print result
echo "Result: $hex_result\n";
This code will output the result of the multiplication as a hexadecimal value.
I'm getting confused on how to do a simple thing, perhaps someone can help me.
At one point of my code I convert a bit array with 10 alarms (0 or 1) to a decimal and save it.
At another point I load the decimal and want to convert it back to a bit array.
This works however the bit array should be always have a length of 10 even if the decimal length is not 10 bites.
See my code:
// Convert array to dec:
$alarms = array(0,0,1,0,0,0,1,0,0,0);
$str = implode("", $alarms);
$dec = bindec($str);
// Convert back to bit array:
$bin = decbin($dec);
echo $bin;
The result of this code is:
10001000
But should be:
0010001000
Thanks!
Here's an idea of how you might implement this.
<?php
// Input array of bits
$inBits = [0,0,1,0,0,0,1,0,0,0];
// Convert to decimal value
$value = bindec(implode('', $inBits));
// Convert back to string of 0/1, adding padding as needed.
$outBitStr = str_pad(decbin($value), count($inBits), '0', STR_PAD_LEFT);
var_dump(implode('', $inBits) === $outBitStr); // TRUE
I am trying to convert a hex string into a signed integer.
I am able to easily transfer it into an unsigned value with hexdec() but this does not give a signed value.
Edit:
code in VB - the two "AA" hex values are representative.
Dim bs(2) As Byte
bs(1) = "AA"
bs(2) = "AA"
Dim s As Short
s = BitConverter.ToInt16(bs, 1)
Check out this comment via php.net:
hexdec() returns unsigned integers. For example hexdec("FFFFFFFE") returns 4294967294, not -2. To convert to signed 32-bit integer you may do:
<?php
echo reset(unpack("l", pack("l", hexdec("FFFFFFFE"))));
?>
As said on the hexdec manual page :
The function can now convert values
that are to big for the platforms
integer type, it will return the value
as float instead in that case.
If you want to get some kind of big integer (not float), you'll need it stored inside a string... This might be possible using BC Math functions.
For instance, if you look in the comments of the hexdec manual page, you'll find this note
If you adapt that function a bit, to avoid a notice, you'll get :
function bchexdec($hex)
{
$dec = 0;
$len = strlen($hex);
for ($i = 1; $i <= $len; $i++) {
$dec = bcadd($dec, bcmul(strval(hexdec($hex[$i - 1])), bcpow('16', strval($len - $i))));
}
return $dec;
}
(This function has be copied from the note I linked to ; and only a bit adapted by me)
And using it on your number :
$h = 'D5CE3E462533364B';
$f = bchexdec($h);
var_dump($f);
The output will be :
string '15406319846273791563' (length=20)
So, not the kind of big float you had ; and seems OK with what you are expecting :
Result from calc.exe =
15406319846273791563
Hope this help ;-)
And, yes, user notes on the PHP documentation are sometimes a real gold mine ;-)
I've been trying to find a decent answer to this question and so I wrote this function which works well for a Hex string input, returning a signed decimal value.
public function hex_to_signed_int($hex_str){
$dec = hexdec($hex_str);
//test is value negative
if($dec & pow(16,strlen($hex_str))/2 ){ return $dec-pow(16,strlen($hex_str));}
return $dec;
}
I have some large HEX values that I want to display as regular numbers, I was using hexdec() to convert to float, and I found a function on PHP.net to convert that to decimal, but it seems to hit a ceiling, e.g.:
$h = 'D5CE3E462533364B';
$f = hexdec($h);
echo $f .' = '. Exp_to_dec($f);
Output: 1.5406319846274E+19 = 15406319846274000000
Result from calc.exe = 15406319846273791563
Is there another method to convert large hex values?
As said on the hexdec manual page:
The function can now convert values
that are to big for the platforms
integer type, it will return the value
as float instead in that case.
If you want to get some kind of big integer (not float), you'll need it stored inside a string. This might be possible using BC Math functions.
For instance, if you look in the comments of the hexdec manual page, you'll find this note
If you adapt that function a bit, to avoid a notice, you'll get:
function bchexdec($hex)
{
$dec = 0;
$len = strlen($hex);
for ($i = 1; $i <= $len; $i++) {
$dec = bcadd($dec, bcmul(strval(hexdec($hex[$i - 1])), bcpow('16', strval($len - $i))));
}
return $dec;
}
(This function has been copied from the note I linked to; and only a bit adapted by me)
And using it on your number:
$h = 'D5CE3E462533364B';
$f = bchexdec($h);
var_dump($f);
The output will be:
string '15406319846273791563' (length=20)
So, not the kind of big float you had ; and seems OK with what you are expecting:
Result from calc.exe =
15406319846273791563
Hope this help ;-)
And, yes, user notes on the PHP documentation are sometimes a real gold mine ;-)
hexdec() switches from int to float when the result is too large to be represented as an int. If you want arbitrarily long values, you're probably going to have to roll your own conversion function to change the hex string to a GMP integer.
function gmp_hexdec($n) {
$gmp = gmp_init(0);
$mult = gmp_init(1);
for ($i=strlen($n)-1;$i>=0;$i--,$mult=gmp_mul($mult, 16)) {
$gmp = gmp_add($gmp, gmp_mul($mult, hexdec($n[$i])));
}
return $gmp;
}
print gmp_strval(gmp_hexdec("D5CE3E462533364B"));
Output: 15406319846273791563
$num = gmp_init( '0xD5CE3E462533364B' ); // way to input a number in gmp
echo gmp_strval($num, 10); // display value in decimal
That's the module to use. Convert it to a function and then use on your numbers.
Note: provide these hex numbers as strings so:
$num = "0x348726837469972346"; // set variable
$gmpnum = gmp_init("$num"); // gmp number format
echo gmp_strval($gmpnum, 10); // convert to decimal and print out
1.5406319846274E+19 is a limited representation of you number. You can have a more complete one by using printf()
printf("%u\n", hexdec($h));
...will output "15406319846273792000". PHP uses floats for such big numbers, so you may lose a bit of precision. If you have to work with arbitrary precision numbers, you may try the bcmath extension. By splitting the hex into two 32-bit words (which should be safe on most systems) you should be able to get more precision. For instance:
$f = bcadd(bcmul(hexdec(substr($h, 0, -8)), 0x100000000), hexdec(substr($h, 8)));
...would set $f to 15406319846273791563.
Convert HEX to DEC is easy.. But, reconstruct back hexadecimal number is very hard.
Try to use base_convert ..
$hexadecimal = base_convert(2826896153644826, 10, 16);
// result: a0b0c0d0e0f1a
Run into this issue while storing 64-bit keys in MySQL database. I was able to get a bit perfect conversion to a 64-bit signed integer (PHP limitation) using a few binary operators: (This code is 16x faster than bchexdec function and resulting variables are using half the memory on average).
function x64toSignedInt($k){
$left = hexdec(substr($k,0,8));
$right = hexdec(substr($k,8,8));
return (int) ($left << 32) | $right;
}
MySQL signed BIGINT datatype is a great match for this as an index or storage in general. HEX(column) is a simple way to convert it back to HEX within the SQL query for use elsewhere.
This solution also uses the BC Math Functions. However, an algorithm is used which does without the bcpow function. This function is a bit shorter and faster than the accepted solution, tested on PHP 7.4.
function hexDecBc(string $hex) : string
{
for ($dec = '0', $i = 0; $i < strlen($hex); $i++) {
$dec = bcadd(bcmul($dec,'16'),(string)hexdec($hex[$i]));
}
return $dec;
}
Make sure to enable gmp extension. ext-gmp
$number = gmp_strval(gmp_init('0x03....')); // outputs: 1234324....
Doesn't intval(var, base) take care of it?
From the PHP Manual.
I have a binary file that is all 8 bit integers. I have tried to use the php unpack() functions but I cant get any of the arguments to work for 1 byte integers. I have tried to combine the data with a dummy byte so that I can use the 'n'/'v' arguments. I am working with a windows machine to do this. Ultimately I would like a function to return an array of integers based on a string of 8 bit binary integers. The code I have tried is below -
$dat_handle = "intergers.dat";
$dat_file = fopen($dat_handle, "rb");
$dat_data = fread($dat_file, 1);
$dummy = decbin(0);
$combined = $dummy.$dat_data;
$result = unpack("n", $combined);
What your looking for is the char datatype. Now there are two version of this, signed (lowercase c) and unsigned (uppercase C). Just use the one that's correct for your data.
<?php
$byte = unpack('c', $byte);
?>
Also, if the data file is just a bunch of bytes and nothing else, and you know it's length, you can do this. (If the length is 16 signed chars in a row.)
<?php
$bytes = unpack('c16', $byte);
?>
If you don't know how many bytes will be in the file, but you know there is only going to be bytes you can use the asterisk code to read until EOF.
<?php
$bytes = unpack('c*', $byte);
?>
The following should do what you want (ord):
$dat_handle = "intergers.dat";
$dat_file = fopen($dat_handle, "rb");
$dat_data = ord(fread($dat_file, 1));
What you are trying to do is retrieve the integer value of the single byte. Because you are reading in single bytes at a time, you will always have exactly one valid ASCII character. ord returns the binary value of that one character.