Bytes Convert to Float (Php)

bytes convert to float (php)

There may be a more direct way, but here you go:

<?php
var_dump(unpack('f', pack('i', 1059760811)));
?>

This is, of course, machine dependent, but I don't know of any machine running PHP that doesn't use IEEE 754 floats.

Convert float to array of bytes in PHP

try to use pack and unpack function:

$f = 26.75;
$ar = unpack("c*", pack("f", $f));

print_r($ar);

Result:

Array
(
  [1] => 0
  [2] => 0
  [3] => -42
  [4] => 65
)

you can find a snippet here

unpacking 4 bytes into a float in PHP

You can split the string in groups of 2 hex characters (1 byte), and convert them in decimal values.

Then, you just need to unpack/pack to get the final float.

To use pack(), you could use the splat operator (...) to unpack values of the array in function's parameters.

$src = '000080c0';

// get ['00','00','80','C0']
$arr = array_map('hexdec', str_split($src, 2));

// pack as bytes, unpack as float
$float = unpack('f', pack("C*", ...$arr));

var_dump($float[1]); // float(-4)

See a working example.

Converting random byte (0-255) to a float in PHP?

Try the simple linear relationship

$f = $r / 255.0;

where $r is the random byte, and $f is the random float.

This way, when $r=255, $f is 1.0 and when $r=127, $f is 0.498

to get 0.5 for r=127 would require a different relationship.

Converting byte-stream into numeric data-type

Just looked up the code for Zend_Crypt_Math_BigInteger_Bcmath and Zend_Crypt_Math_BigInteger_Gmp which deals with this problem:

Using BCmath (Big-Endian)

This is essentially the solution posted by Chad Birch.

public static function bc_binaryToInteger($operand)
{
    $result = '0';
    while (strlen($operand)) {
        $ord = ord(substr($operand, 0, 1));
        $result = bcadd(bcmul($result, 256), $ord);
        $operand = substr($operand, 1);
    }
    return $result;
}

Using GMP (Big-Endian)

Same algorithem - just different function names.

public static function gmp_binaryToInteger($operand)
{
    $result = '0';
    while (strlen($operand)) {
        $ord = ord(substr($operand, 0, 1));
        $result = gmp_add(gmp_mul($result, 256), $ord);
        $operand = substr($operand, 1);
    }
    return gmp_strval($result);
}

Changing the algorithem to use Litte-Endian byte-order is quite simple: just read the binary data from end to start:

Using BCmath (Litte-Endian)

public static function bc_binaryToInteger($operand)
{
    // Just reverse the binray data
    $operand = strrev($operand);
    $result = '0';
    while (strlen($operand)) {
        $ord = ord(substr($operand, 0, 1));
        $result = bcadd(bcmul($result, 256), $ord);
        $operand = substr($operand, 1);
    }
    return $result;
}

Using GMP (Litte-Endian)

public static function gmp_binaryToInteger($operand)
{
    // Just reverse the binray data
    $operand = strrev($operand);
    $result = '0';
    while (strlen($operand)) {
        $ord = ord(substr($operand, 0, 1));
        $result = gmp_add(gmp_mul($result, 256), $ord);
        $operand = substr($operand, 1);
    }
    return gmp_strval($result);
}

PHP convert String number with whitespace to Float

Most likely you have a non visible character as the thousand separator character. It's more safe to filter all characters except digits and . when sanitizing the input string. This can be achieved with the preg_replace function.

Your script can be modified to something like this:

$a = "3 999.99";
$b = "1 500.11";

$aa = floatval(preg_replace('/[^0-9.]/', '', $a));
$bb = floatval(preg_replace('/[^0-9.]/', '', $b));

$c = $aa - $bb;
echo $aa . ' - ' . $bb . ' = ' . $c;

Additionally, it's a bit dangerous and non exact to use floats when handling money in particular. Please have a look at this repository which helps a lot with this problem: https://github.com/moneyphp/money

PHP: convert string to float (only if string represents a float)

You can use is_numeric() function to check variable which might contain a number.
For example:

$a = "1.23";
if (is_numeric($a)) {
    $a = (float)$a;
}

$b = "1.2 to 1.3";
if (is_numeric($b)) {
    $b = (float)$b;
}

var_dump([
    'a' => $a,
    'b' => $b
]);

Output

array (size=2) 'a' => float 1.23 'b' => string '1.2 to 1.3'
(length=10)

How to convert byte array to integer in php?

Why not treat it like the math problem it is?

$i = ($ar[3]<<24) + ($ar[2]<<16) + ($ar[1]<<8) + $ar[0];

Format bytes to kilobytes, megabytes, gigabytes

function formatBytes($bytes, $precision = 2) { 
    $units = array('B', 'KB', 'MB', 'GB', 'TB'); 

    $bytes = max($bytes, 0); 
    $pow = floor(($bytes ? log($bytes) : 0) / log(1024)); 
    $pow = min($pow, count($units) - 1); 

    // Uncomment one of the following alternatives
    // $bytes /= pow(1024, $pow);
    // $bytes /= (1 << (10 * $pow)); 

    return round($bytes, $precision) . ' ' . $units[$pow]; 
} 

(Taken from php.net, there are many other examples there, but I like this one best :-)

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