Description:
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I have a member function which is been called in the destructor of this object. The called function has to write a string into a file, which shall be stored in a subdirectory. 
In my case its F:\php\logs (php is the dir where the script is stored, in the \logs dir shall the created file be stored). The first problem I recognized was that PHP can't read the current directory in the function, the second one is that it creates files in a totally different directory. If I tell this function "mkdir("./logs/");", it won't create a subdir called "logs" in F:\php, but in D:\ (-> D:\logs)! 
If I write the absolute directory, the thing works, but it's useless on a webspace.
My php.ini hasn't set anything to D:\ just PHP is installed in D:\php\

Reproduce code:
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class someclass
{   // Constructors, functions, vars...
    public function someclass_make_file($mode)    {
        if(defined('DEBUG_LOG')) { 
			switch($mode)  { 
				case 3:
	  $dl = $this->debug_log;  // "Info"
	  $dfl = fopen("logs/".time().".txt", "a");
        fwrite($dfl, $dl);
	  fclose($dfl); 
	  break;
			}
		}
		return true;
    }
    public funtion __construct()
    {
       $this->someclass_make_file(3)
    }
}


Expected result:
----------------
A file F:\php\logs\1134123412.txt

Actual result:
--------------
A file D:\logs\1134123412.txt or non has been created.