php创建文件并写入信息

$myfile = fopen("c:\newfile.txt", "w") or die("Unable to open file!");
            $txt = "AAA ";
            fwrite($myfile, $txt);            
            
            $txt = sizeof($_FILES["picfile"]);
            fwrite($myfile, $txt);            
            
            $txt = "BBB ";
            fwrite($myfile, $txt);
            fclose($myfile);