各位php的高手帮帮忙，我在写论坛时有到了困难，请帮帮忙

我根据旅行改的
199行function readfromfile ($path) {
// returns all data in $path, or nothing if it does not exist

if(file_exists($path)==0) {
return "";
} else {
$filesize=filesize($path);
$filenum=fopen($path,"r");
flock($filenum,LOCK_SH);
$filestuff=fread($filenum,$filesize);
fclose($filenum);
return $filestuff;
}
}
运行时会出来
inWarning: fopen("datafile/config.php","w") - No such file or directory in adminglobal.php on line 199
Warning: Supplied argument is not a valid File-Handle resource in adminglobal.php on line 200
Warning: Supplied argument is not a valid File-Handle resource in adminglobal.php on line 201
Warning: Supplied argument is not a valid File-Handle resource in adminglobal.php on line 202
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我的QQ是：5615182
帮我看看，谢谢