how to display the binary form of the file with php?

Every file can be displayed in the binary form no matter which encoding the file is.(utf-8 gbk iso-8859-1 latin-1) xxd filename can do the trick. Now i want to do with php,here is my try. <?php $target="test.txt"; $file_handle = fopen($target, "rb"); while (!feof($file_handle)) { $byte = fread($file_handle,1); echo $byte; } fclose($file_handle ); ?> It is unlucky that all the character is not displayed on binary form,how to fix echo $byte ?