CCK > user reference field > default value > php code to choose currently logged in user from the list

Hello,

Thanks to everyone in this great community. I am new to Drupal and make my first steps in understanding.
So far I could figure out every solution with the infos I found here. But not in this case.

I use CCK and the USER REFERENCE modul/field. When I enter the configuration of that field in my content type I see the option 'Default Value' and the suboption to enter php code to define the default value.
That is exactly what I need (I think).

What code would I have to enter there to select by default the currently logged in user.

Can anybody help me with this code ? I have no clue about php

Below the PHP default value entry field there is the following hint:

"Advanced Usage Only: PHP code that returns a default value. Should not include

delimiters. If this field is filled out, the value returned by this code will override any value specified above. Expected format :

array(
0 => array('uid' => value for uid),
// You'll usually want to stop here. Provide more values
// if you want your 'default value' to be multi-valued :
1 => array('uid' => value for uid),
2 => ...
);

Using devel.module's 'devel load' tab on a story content page might help you figure out the expected format."

Thank you so much ... I hope I learn fast to be able to contribute back to the community soon ...