php 字符串与2进制的转换

<?php function bin2text($bin_str) {     $text_str = '';     $chars = EXPLODE("\n", CHUNK_SPLIT(STR_REPLACE("\n", '', $bin_str), 8));     $_I = COUNT($chars);     FOR($i = 0; $i < $_I; $text_str .= CHR(BINDEC($chars[$i])), $i  );     RETURN $text_str; }  function text2bin($txt_str) {     $len = STRLEN($txt_str);     $bin = '';     FOR($i = 0; $i < $len; $i++)     {         $bin .= STRLEN(DECBIN(ORD($txt_str[$i]))) < 8 ? STR_PAD(DECBIN(ORD($txt_str[$i])), 8, 0, STR_PAD_LEFT) : DECBIN(ORD($txt_str[$i]));     }     RETURN $bin; } echo text2bin('Isn't this cool?'); ?>