PHP实例:检测并清除文件开头的BOM信息

<?php
ini_set('memory_limit', '-1'); 
/*检测并清除BOM*/ 
$basedir = dirname(__FILE__);//扫描当前文件路径 可自动设置 
$auto = 1; 
checkdir($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($dirname); 
                } 
            } 
        }//end while 
    closedir($dh); 
    }//end if($dh 
}//end function 
function checkBOM($filename){ 
    global $auto;  // www.jb200.com
    $contents = file_get_contents($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, $rest); 
            return "<font color=red>BOM found, automatically removed.</font>"; 
        }else{ 
            return ("<font color=red>BOM found.</font>"); 
        } 
    } 
    else return ("BOM Not Found."); 
}//end function 
function rewrite($filename, $data){ 
    $filenum = fopen($filename, "w"); 
    flock($filenum, LOCK_EX); 
    fwrite($filenum, $data); 
    fclose($filenum); 
}//end function