php批量检测并去除BOM头的代码

开发中会遇到BOM头, 导致程序无法执行. 浏览器返回接口如下图:

去除BOM头解决方法:
<?php
ini_set('memory_limit','1024M'); 
function checkdir($basedir) {    
    if ($dh = opendir ( $basedir )) {    
        while ( ($file = readdir ( $dh )) !== false ) {    
            if ($file != '.' && $file != '..') {    
                if (! is_dir ( $basedir . "/" . $file )) { // 如果是文件    
                    echo "filename: $basedir/$file " . checkBOM ( "$basedir/$file" ) . " <br>";    
                } else {    
                    $dirname = $basedir . "/" .$file; // 如果是目录    
                    checkdir ( $dirname );    
                }    
            }    
        }    
        closedir ( $dh );    
    }    
}    

function checkBOM($filename) {    
    global $auto;    
    $contents = file_get_contents ( $filename );    
    $charset [] = substr ( $contents, ,  );    
    $charset [] = substr ( $contents, ,  );    
    $charset [] = substr ( $contents, ,  );    
    if (ord ( $charset [] ) ==  && ord ( $charset [] ) ==  && ord ( $charset [] ) == ) { // BOM 的前三个字符的ASCII 码分别为 239 187 191    
        if ($auto == ) {    
            $rest = substr ( $contents,  );    
            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 );    
} 

$auto=;
$dir='D:/web/';//项目文件路径
checkDir($dir);
?>