file - Saving hex data in binary using PHP does not work properly -

i learning php , files , trying write code put data in binary file.

here's code:

write

<?php  echo "\n\nwrite: \n\n"; $c = array(); $data = '';  $c['name'] = 'abcdefghijklmnopqrstuvwxyz'; $data .= implode('', $c); $fp = fopen('test.bin', 'wb');  $len = strlen($data); echo "\nfile content: $data (strlen: $len)\n\n"; ($i = 0; $i < $len; ++$i) {     $hx = dechex(ord($data{$i}));     fwrite($fp, pack("c", $hx)); } echo "last char is: $hx mean: "; echo chr(hexdec('7a')); echo "\n--------------------------------------------\n"; fclose($fp); 

output

file content: abcdefghijklmnopqrstuvwxyz (strlen: 26)  last char is: 7a mean: z 

read

<?php  echo "\n--------------------------------------------\n"; echo "\n\nread: \n\n"; $fp = fopen('test.bin', 'rb'); $fseek = fseek($fp, 0, seek_set); if($fseek == -1) {     return false; } $data = fread($fp, 26); $arr = unpack("c*", $data); $return = ''; foreach($arr $val) {     $return .= chr(hexdec($val)); } $n = ''; $arr = array(); $arr['name'] = substr($return, 0, 26);  print_r($arr);  echo "\n--------------------------------------------\n"; 

output

array (     [name] => abcdefghipqrstuvwxy ) 

where missing letters z, m, n or o ?

edit 6-3-14 7h36 am: have .bin file not plain text if possible

you trying set hex chars in char (c - unsigned char) instruction.

echo "\t"; foreach( array('0x41', 65, 'a') $o ) echo $o."\t"; echo "\n"; foreach( array('c*','c*','a*','a*','h*','h*','v*','n*','s*') $o ){     echo $o . "\t";     foreach( array(0x41, 65, "a") $oo ) {         echo pack($o, $oo);         echo "\t";     }     echo "\n"; } 

if run this, see how pack works 3 different values of (hex, dec , normal).

you have use h instruction accomplish need.

function writetofile($data) {     $fp = fopen(filename, 'wb');     $len = strlen($data);     ($i = 0; $i < $len; ++$i) {         $hx = dechex(ord($data[$i]));         $result = fwrite($fp, pack("h*", $hx));         if(!$result) {             // show         }     }     fclose($fp); } 

now, read data. need use same 1 h and split string (split using str_split parameter 2 since it's hex 00 = 0 , ff = 255 - assuming won't go on 255). since h returns array single element. once string back, need convert number ord in writetofile using chr function.

function readfromfile($lenght, $pos = 0) {     $return = '';     $fp = fopen(filename, 'rb');     if(!$fp) {         // show     }     $fseek = fseek($fp, $pos, seek_set);     if($fseek == -1) {         // show     }     $data = fread($fp, $lenght);     $data = unpack("h*", $data);     $arr = str_split(current($data), 2);     foreach($arr $val) {         $return .= chr(hexdec($val));     }     return $return; } 

now, create string , write file:

$data = 'this should work properly, stackoverflow!'; $len = strlen($data); writetofile($data); 

then read back:

echo readfromfile($len); 

the content of file this:

e<86><96>7^b7<86>öwÆf^bwö'¶^b^g'ö^gv'Æ<97>Â^bg<86>^væ¶7^bfö'^b5g^v6¶ôgv'dÆöw^r