Encoding / decoding string in hexadecimal and reverse

Question

For a string that can contain any character (including Unicode characters), how can I convert this string to a hexadecimal representation and then cancel and get from a hexadecimal string?

Answer 1

Use pack() and unpack() :

 function hex2str( $hex ) { return pack('H*', $hex); } function str2hex( $str ) { return array_shift( unpack('H*', $str) ); } $txt = 'This is test'; $hex = str2hex( $txt ); $str = hex2str( $hex ); echo "{$txt} => {$hex} => {$str}\n"; 

will create

This is test => 546869732069732074657374 => This is a test

Answer 2

Use the following function:

 <?php function bin2hex($str) { $hex = ""; $i = 0; do { $hex .= dechex(ord($str{$i})); $i++; } while ($i < strlen($str)); return $hex; } // Look what happens when ord($str{$i}) is 0...15 // you get a single digit hexadecimal value 0...F // bin2hex($str) could return something like 4a3, // decimals(74, 3), whatever the binary value is of those. function hex2bin($str) { $bin = ""; $i = 0; do { $bin .= chr(hexdec($str{$i}.$str{($i + 1)})); $i += 2; } while ($i < strlen($str)); return $bin; } // hex2bin("4a3") just broke. Now what? // Using sprintf() to get it right. function bin2hex($str) { $hex = ""; $i = 0; do { $hex .= sprintf("%02x", ord($str{$i})); $i++; } while ($i < strlen($str)); return $hex; } // now using whatever the binary value of decimals(74, 3) // and this bin2hex() you get a hexadecimal value you can // then run the hex2bin function on. 4a03 instead of 4a3. ?> 

Source: http://php.net/manual/en/function.bin2hex.php