如何清除UTF-8檔的BOM檔頭

最近在玩PHP的時候，遇到下面這個錯誤訊息：

Warning: Cannot modify header information – headers already sent by

經查才發現是PHP在執行UTF-8的檔案時，BOM檔頭一直無法清掉。

將下列程式碼儲存成PHP檔，並將此檔案複製至根目錄下執行，這樣就會自動檢查所有檔案，並清除UTF-8檔的BOM檔頭。

  1: <?php
  2: //remove the utf-8 boms
  3: //by magicbug at gmail dot com
  4: if (isset($_GET[’dir’])){ //config the basedir
  5: $basedir=$_GET[’dir’];
  6: }else{
  7: $basedir = ".";
  8: }
  9: $auto = 1;
 10: 
 11: checkdir($basedir);
 12: 
 13: function checkdir($basedir){
 14: if ($dh = opendir($basedir)) {
 15: while (($file = readdir($dh)) !== false) {
 16: if ($file != "." && $file != ".."){
 17: if (!is_dir($basedir."/".$file)) {
 18: echo "filename: $basedir/$file ".checkBOM("$basedir/$file")."";
 19: }else{
 20: $dirname = $basedir."/".$file;
 21: checkdir($dirname);
 22: }
 23: }
 24: }
 25: closedir($dh);
 26: }
 27: }
 28: 
 29: function checkBOM ($filename) {
 30: global $auto;
 31: $contents = file_get_contents($filename);
 32: $charset[1] = substr($contents, 0, 1);
 33: $charset[2] = substr($contents, 1, 1);
 34: $charset[3] = substr($contents, 2, 1);
 35: if (ord($charset[1]) == 239 && ord($charset[2]) == 187 && ord($charset[3]) == 191) {
 36: if ($auto == 1) {
 37: $rest = substr($contents, 3);
 38: rewrite ($filename, $rest);
 39: return ("BOM found, automatically removed.
 40: ");
 41: } else {
 42: return ("BOM found.
 43: ");
 44: }
 45: }
 46: else return ("BOM Not Found.
 47: ");
 48: }
 49: 
 50: function rewrite ($filename, $data) {
 51: $filenum = fopen($filename, "w");
 52: flock($filenum, LOCK_EX);
 53: fwrite($filenum, $data);
 54: fclose($filenum);
 55: }
 56: ?>