PHP 版去bom头

原理：

找出文件前3个字符

如果它们对应的ASCII 值分别是  239，187，191

则判断为bom头,去掉前3个字符.

代码实现如下：

$basedir =  isset($_GET['dir'])  ? $_GET['dir'] : ".";

$auto    = 1;

$auto    =  isset($_GET['auto']) ? $_GET['auto'] : $auto;

checkdir($basedir);

function checkdir($basedir)

{

    if ($dh = opendir($basedir)) {

        while (($file = readdir($dh)) !== false) {

            if ($file != '.' && $file != '..') {

                if (!is_dir($basedir . "/" . $file)) {

                    echo "filename: $basedir/$file " . checkBOM("$basedir/$file") . " <br>";

                } else {

                    $dirname = $basedir . "/" . $file;

                    checkdir($dirname);

                }

            }

        }

        closedir($dh);

    }

}

function checkBOM($filename)

{

    global $auto;

    $contents   = file_get_contents($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) {

        if ($auto == 1) {

            $rest = substr($contents, 3);

            rewrite($filename, $rest);

            return ("<font color='red'>BOM found, automatically removed.</font>");

        } else {

            return ("<font color='red'>BOM found.</font>");

        }

    } else

        return ("BOM Not Found.");

}

function rewrite($filename, $data)

{

    $filenum = fopen($filename, "w");

    flock($filenum, LOCK_EX);

    fwrite($filenum, $data);

    fclose($filenum);

}