YourPHP后台登陆验证码不显示问题解决方法

<?php
/*检测并清除BOM*/ 
if(isset($_GET['dir'])){  
$basedir=$_GET['dir'];  
}else{  
$basedir = '.';  
}   
$auto = 1;   
checkdir($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;  
$contents = file_get_contents($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  
?>