hex2bin()

(PHP 5 >= 5.4.0, PHP 7)

转换十六进制字符串为二进制字符串

说明

hex2bin(string $data) : string

转换十六进制字符串为二进制字符串。

这个函数不是转换十六进制数字为二进制数字。这种转换可以使用base_convert()函数。

参数

$data

十六进制表示的数据

返回值

返回给定数据的二进制表示或者在失败时返回FALSE。

错误／异常

如果输入的十六进制字符串是奇数长数或者无效的十六进制字符串将会抛出E_WARNING级别的错误。

更新日志

范例

Example #1hex2bin()例子

<?php
$hex = hex2bin("6578616d706c65206865782064617461");
var_dump($hex);
?>

以上例程的输出类似于：

string(16) "example hex data"

参见

• bin2hex()函数把包含数据的二进制字符串转换为十六进制值
• unpack()Unpack data from binary string

The function hex2bin does not exist in PHP5.
You can use 'pack' instead :
$binary_string = pack("H*" , $hex_string);

I modified the function by Johnson a bit so it can be used as a drop-in-replacement. You don't need to worry about upgrading php because when it is upgraded, it will use the build in function.
<?php
if ( !function_exists( 'hex2bin' ) ) {
  function hex2bin( $str ) {
    $sbin = "";
    $len = strlen( $str );
    for ( $i = 0; $i < $len; $i += 2 ) {
      $sbin .= pack( "H*", substr( $str, $i, 2 ) );
    }
    return $sbin;
  }
}
?>

$test = bin2hex('sample ...');
echo _hex2bin($test);
// another hex2bin replacement
function _hex2bin($result) {
  $out = '';
  for($c=0;$c<strlen($result);$c+=2) {
    $out .= chr(hexdec($result[$c].$result[$c+1]));
  } //end for
  return (string) $out;
}

The function pack("H*" , $hex_string); will not work as expected if $hex_string contains an odd number of hexadecimal digits.
For example:
<?php echo ord(pack("H*", 'F')); ?>
will return 240 not 15. Use pack("H*", '0F'); instead.

For those who have php version prior to 5.4, i have a solution to convert hex to binary. It works for me in an encryption and decryption application.
<?php
    function hextobin($hexstr)
  {
    $n = strlen($hexstr);
    $sbin="";  
    $i=0;
    while($i<$n)
    {    
      $a =substr($hexstr,$i,2);      
      $c = pack("H*",$a);
      if ($i==0){$sbin=$c;}
      else {$sbin.=$c;}
      $i+=2;
    }
    return $sbin;
  }
?>

If you want to convert hex to GUID format (In my case, it was to convert GUID from MSSQL database) :
<?php
function hex2Guid($hex)
{
  $hex = [
    substr($hex, 0, 8),
    substr($hex, 8, 4),
    substr($hex, 12, 4),
    substr($hex, 16, 4),
    substr($hex, 20),
  ];
  $order[0] = [6, 7, 4, 5, 2, 3, 0, 1];
  $order[1] = [2, 3, 0, 1];
  $order[2] = [2, 3, 0, 1];
  $order[3] = [0, 1, 2, 3];
  $order[4] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
  $result = "";
  for($num = 0; $num < count($order); $num++)
  {
    for($i = 0; $i < count($order[$num]); $i++)
    {
      $result .= $hex[$num][$order[$num][$i]];
    }
    if($num != count($order) -1)
    {
      $result .= "-";
    }
  }
  return strtoupper($result);
}
Example : 
echo hex2Guid("64d3938b7008cd4bad5ffe56755d163f");
// return 8B93D364-0870-4BCD-AD5F-FE56755D163F

A drop-in hex2bin emulator which behaves just like the the one in v5.5.1.
<?php
if (!function_exists('hex2bin')) {
  function hex2bin($data) {
    static $old;
    if ($old === null) {
      $old = version_compare(PHP_VERSION, '5.2', '<');
    }
    $isobj = false;
    if (is_scalar($data)  ||  (($isobj = is_object($data)) && method_exists($data, '__toString'))) {
      if ($isobj && $old) {
        ob_start();
        echo $data;
        $data = ob_get_clean();
      }
      else {
        $data = (string) $data;
      }
    }
    else {
      trigger_error(__FUNCTION__.'() expects parameter 1 to be string, ' . gettype($data) . ' given', E_USER_WARNING);
      return;//null in this case
    }
    $len = strlen($data);
    if ($len % 2) {
      trigger_error(__FUNCTION__.'(): Hexadecimal input string must have an even length', E_USER_WARNING);
      return false;
    }
    if (strspn($data, '0123456789abcdefABCDEF') != $len) {
      trigger_error(__FUNCTION__.'(): Input string must be hexadecimal string', E_USER_WARNING);
      return false;
    }
    return pack('H*', $data);
  }
}
?>

A way to convert hex strings in the form "0x123ABC" to integer is to use the function base_convert("0x123ABC", 16, 10)

Case of an incomplete hex string following function may help:
<?php
function make2validhex($data){
  $data = (string) $data;
  $len = strlen($data);
  if($len % 2) {
    return substr($data, 0, $len -1);
  }
  return $data;
}
?>
test:
<?php
$string="not complete"; 
echo $string;
echo PHP_EOL;
$hex = bin2hex($string); //"6e6f7420636f6d706c657465"
echo $hex; 
echo PHP_EOL;
$deff = substr ($hex, 0, strlen($hex) -1);//"6e6f7420636f6d706c65746"
echo $deff;
echo PHP_EOL;
echo hex2bin(make2validhex($deff)); //"not complet"
echo PHP_EOL;
?>

replace
function Hex2Bin($data) {
  $BinData = "";
  for ($i=0;$i<strlen($data);$i+=2)
    $BinData .= chr( HexDec( substr($data,$i,2) ) );
  return $BinData;
With
function hextobin($hexstr) 
  { 
    $n = strlen($hexstr); 
    $sbin="";  
    $i=0; 
    while($i<$n) 
    {    
      $a =substr($hexstr,$i,2);      
      $c = pack("H*",$a); 
      if ($i==0){$sbin=$c;} 
      else {$sbin.=$c;} 
      $i+=2; 
    } 
    return $sbin;

Ran into an interesting case with hex2bin and php5.5.12 while upgrading from 5.3.3 -> 5.5.12
The previous code had redeclared the hex2bin function with the $binary_string = pack("H*" , $hex_string) trick. 
php5.5.12 would have none of that. The solution, albeit a hacky one, was doing a find an replace of hex2bin to 'hex3bin' for the whole site directory.