用PHP去掉文件头的Unicode签名(BOM)方法

<?php//此文件用于快速测试UTF8编码的文件是不是加了BOM，并可自动移除//By Bob Shen$basedir="."; //修改此行为需要检测的目录，点表示当前目录$auto=1; //是否自动移除发现的BOM信息。1为是，0为否。//以下不用改动if ($dh = opendir($basedir)) {while (($file = readdir($dh)) !== false) {if ($file!='.' && $file!='..' && !is_dir($basedir."/".$file)) echo "filename: $file ".checkBOM("$basedir/$file")." <br>";}closedir($dh);}function checkBOM ($filename) {$contents=file_get_contents($filename);$charset[1]=substr($contents, 0, 1);$charset[2]=substr($contents, 1, 1);$charset[3]=substr($contents, 2, 1);if (ord($charset[1])==239 && ord($charset[2])==187 && ord($charset[3])==191) {$rest=substr($contents, 3);rewrite ($filename, $rest);return true;}else return ("BOM Not Found.");}function rewrite ($filename, $data) {$filenum=fopen($filename,"w");flock($filenum,LOCK_EX);fwrite($filenum,$data);fclose($filenum);}?>