dynamic link

Making a site on which multiple members can blog, now I need to make a dynamic link in a widget (php) which links to the overview of the logged in member’s page which shows all his-her personal blogposts.

So the link should something like this
https://www.xyz.com/?cat_id=1&author=4

The ?cat_id=1 should be static but the author=4 should point to the logged in members ID

Hope I made myself clear…

Can someone help me with the code for this please, you’d make me very happy!!!