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: $hex_result\n";
This code will output the result of the multiplication as a hexadecimal value.
Related
I know this is a pretty silly question, but I don't know what to do.
I have an arbitrary binary number, say,
1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111
I want to convert it to Base 64 using PHP - and every way I try gives me a different result. Even different online converters convert it differently:
http://home2.paulschou.net/tools/xlate/
http://convertxy.com/index.php/numberbases/
PHP's base_convert only works up to base36, and base64_encode expects a string.
What do I do?
UPDATE: I implemented the solution functions suggested by #binaryLV, and it did work well.
However, I compared the results to PHP's built-in base_convert. It turned out that base_convert to base36 returns shorter values that the custom base64 function! (And yes, I did prepend a '1' to all the binary numbers to ensure leading zeros aren't lost).
I have noticed, too, that base_convert is quite innacurate with large numbers. So I need is a function which works like base_convert, but accurately and, preferably, up to base 64.
Length of a string in example is 160. It makes me think that it holds info about 160/8 characters. So,
split string into parts, each part holds 8 binary digits and describes single character
convert each part into a decimal integer
build a string from characters, that are made from ASCII codes from 2nd step
This will work with strings with size n*8. For other strings (e.g., 12 binary digits) it will give unexpected results.
Code:
function bin2base64($bin) {
$arr = str_split($bin, 8);
$str = '';
foreach ( $arr as $binNumber ) {
$str .= chr(bindec($binNumber));
}
return base64_encode($str);
}
$bin = '1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111';
echo bin2base64($bin);
Result:
kDICQIMBEFjDBxwMBJiAASBYwgc=
Here's also function for decoding it back to string of binary digits:
function base64bin($str) {
$result = '';
$str = base64_decode($str);
$len = strlen($str);
for ( $n = 0; $n < $len; $n++ ) {
$result .= str_pad(decbin(ord($str[$n])), 8, '0', STR_PAD_LEFT);
}
return $result;
}
var_dump(base64bin(bin2base64($bin)) === $bin);
Result:
boolean true
PHP has a built in base 64 encoding function, see documentation here. If you want the decimal value of the binary string first use bin2dec, there are similar functions for hexadecimals by the way. The documentation is your friend here.
[EDIT]
I might have misunderstood your question, if you want to convert between actual bases (base 2 and 64) use base_convert
$number = 1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111;
echo base64_encode ($number);
This is if you want the exact string be converted into Base 64.
To convert a binary number (2 base) to a 64 base use the base_convert function.
$number = 1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111;
base_convert ($number , 2, 64);
I am extracting a serial from a digital certificate using the built-in OpenSSL library, however, I am having trouble converting this number to hex with precision.
The extracted number is originally in decimal but I need to have it in hex.
The number I am trying to convert is: 114483222461061018757513232564608398004
Here is what I've tried:
dechex() did not work, it returns: 7fffffffffffffff
The closest I could get was this function from the php.net page but it does not convert the whole number on part of it.
function dec2hex($dec) {
$hex = ($dec == 0 ? '0' : '');
while ($dec > 0) {
$hex = dechex($dec - floor($dec / 16) * 16) . $hex;
$dec = floor($dec / 16);
}
return $hex;
}
echo dec2hex('114483222461061018757513232564608398004');
//Result: 5620aaa80d50fc000000000000000000
Here is what I am expecting:
Decimal number: 114483222461061018757513232564608398004
Expected hex: 5620AAA80D50FD70496983E2A39972B4
I can see the correction conversion here:
https://www.mathsisfun.com/binary-decimal-hexadecimal-converter.html
I need a PHP solution.
The problem is that The largest number that can be converted is ... 4294967295 - hence why it's not working for you.
This answer worked for me during a quick test, assuming you have bcmath installed on your server, and you can obtain the number as a string to start with. If you can't, i.e. it begins life as numeric variable, you'll immediately reach PHP's float limit.
// Credit: joost at bingopaleis dot com
// Input: A decimal number as a String.
// Output: The equivalent hexadecimal number as a String.
function dec2hex($number)
{
$hexvalues = array('0','1','2','3','4','5','6','7',
'8','9','A','B','C','D','E','F');
$hexval = '';
while($number != '0')
{
$hexval = $hexvalues[bcmod($number,'16')].$hexval;
$number = bcdiv($number,'16',0);
}
return $hexval;
}
Example:
$number = '114483222461061018757513232564608398004'; // Important: already a string!
var_dump(dec2hex($number)); // string(32) "5620AAA80D50FD70496983E2A39972B4"
Ensure you pass a string into that function, not a numeric variable. In the example you provided in the question, it looks like you can obtain the number as a string initially, so should work if you have bc installed.
Answered by lafor.
How to convert a huge integer to hex in php?
function bcdechex($dec)
{
$hex = '';
do {
$last = bcmod($dec, 16);
$hex = dechex($last).$hex;
$dec = bcdiv(bcsub($dec, $last), 16);
} while($dec>0);
return $hex;
}
Example:
$decimal = '114483222461061018757513232564608398004';
echo "Hex decimal : ".bcdechex($decimal);
This is a big integer, so you need to use a big-integer library like GMP:
echo gmp_strval('114483222461061018757513232564608398004', 16);
// output: 5620aaa80d50fd70496983e2a39972b4
Try this 100% working for any number
<?php
$dec = '114483222461061018757513232564608398004';
// init hex array
$hex = array();
while ($dec)
{
// get modulus // based on docs both params are string
$modulus = bcmod($dec, '16');
// convert to hex and prepend to array
array_unshift($hex, dechex($modulus));
// update decimal number
$dec = bcdiv(bcsub($dec, $modulus), 16);
}
// array elements to string
echo implode('', $hex);
?>
For a project I need to read in information from MQTT. The payload is filled with protobuf information, that needs to be converted.
For a certain value I receive 5.6904566139035E-28 as float. Using http://www.exploringbinary.com/floating-point-converter/ I can convert this when I tick single and raw hexadecimal value, then I receive 12345678, the value I should have (I know what is sent).
But now I need to do that conversion in PHP. I haven't any idea how this could be done. After some reading I figured out it is a Floating Point, but how to convert this like done on that website.
Is there someone that can help me with this!
Thanks a lot!
With the quite cryptic pack and unpack functions, it can be done in a one-liner:
function rawSingleHex($num) {
return strrev(unpack('h*', pack('f', $num))[1]);
}
This "packs" the number as its binary representation, then "unpacks" it in an array with one element: the binary representation in hexadecimal format. This format has the digits in the reversed order, so the function reverses that in the final result.
Call it by passing the floating point number:
echo rawSingleHex(5.6904566139035E-28);
Output:
12345678
Without pack/pack
(this was my original answer, but with the first option being available, this is not the advised way to proceed)
The binary format is explained in Wikipedia's article on the Single-precision floating-point format.
Here is a PHP function that implements the described procedure:
function rawSingleHex($num) {
if ($num == 0) return '00000000';
// set sign bit, and add another, higher one, which will be stripped later
$sign = $num < 0 ? 0x300 : 0x200;
$significant = abs($num);
$exponent = floor(log($significant, 2));
// get 24 most significant binary bits before the comma:
$significant = round($significant / pow(2, $exponent-23));
// exponent has exponent-bias format:
$exponent += 127;
// format: 1 sign bit + 8 exponent bits + 23 significant bits,
// without left-most "1" of significant
$bin = substr(decbin($sign + $exponent), 1) .
substr(decbin($significant), 1);
// assert that result has correct number of bits:
if (strlen($bin) !== 32) {
return "unexpected error";
}
// convert binary representation to hex, with exactly 8 digits
return str_pad(dechex(bindec($bin)), 8, "0", STR_PAD_LEFT);
}
It outputs the same as in the first solution.
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
$number = gmp_strval(gmp_init('0x03....')); // outputs: 1234324....
Doesn't intval(var, base) take care of it?
From the PHP Manual.
I know this is a pretty silly question, but I don't know what to do.
I have an arbitrary binary number, say,
1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111
I want to convert it to Base 64 using PHP - and every way I try gives me a different result. Even different online converters convert it differently:
http://home2.paulschou.net/tools/xlate/
http://convertxy.com/index.php/numberbases/
PHP's base_convert only works up to base36, and base64_encode expects a string.
What do I do?
UPDATE: I implemented the solution functions suggested by #binaryLV, and it did work well.
However, I compared the results to PHP's built-in base_convert. It turned out that base_convert to base36 returns shorter values that the custom base64 function! (And yes, I did prepend a '1' to all the binary numbers to ensure leading zeros aren't lost).
I have noticed, too, that base_convert is quite innacurate with large numbers. So I need is a function which works like base_convert, but accurately and, preferably, up to base 64.
Length of a string in example is 160. It makes me think that it holds info about 160/8 characters. So,
split string into parts, each part holds 8 binary digits and describes single character
convert each part into a decimal integer
build a string from characters, that are made from ASCII codes from 2nd step
This will work with strings with size n*8. For other strings (e.g., 12 binary digits) it will give unexpected results.
Code:
function bin2base64($bin) {
$arr = str_split($bin, 8);
$str = '';
foreach ( $arr as $binNumber ) {
$str .= chr(bindec($binNumber));
}
return base64_encode($str);
}
$bin = '1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111';
echo bin2base64($bin);
Result:
kDICQIMBEFjDBxwMBJiAASBYwgc=
Here's also function for decoding it back to string of binary digits:
function base64bin($str) {
$result = '';
$str = base64_decode($str);
$len = strlen($str);
for ( $n = 0; $n < $len; $n++ ) {
$result .= str_pad(decbin(ord($str[$n])), 8, '0', STR_PAD_LEFT);
}
return $result;
}
var_dump(base64bin(bin2base64($bin)) === $bin);
Result:
boolean true
PHP has a built in base 64 encoding function, see documentation here. If you want the decimal value of the binary string first use bin2dec, there are similar functions for hexadecimals by the way. The documentation is your friend here.
[EDIT]
I might have misunderstood your question, if you want to convert between actual bases (base 2 and 64) use base_convert
$number = 1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111;
echo base64_encode ($number);
This is if you want the exact string be converted into Base 64.
To convert a binary number (2 base) to a 64 base use the base_convert function.
$number = 1001000000110010000000100100000010000011000000010001000001011000110000110000011100011100000011000000010010011000100000000000000100100000010110001100001000000111;
base_convert ($number , 2, 64);