Logic hooks

There are no addresses for Cases module out-of-the-box, is that a custom-added field? if so, what is the name of the custom field?
What condition (event) should trigger an assignment of some Contact's (which one's?) address to the Case?
Are you looking for an answer feasible for Sugar Developer or Sugar Admin?

I have add address field in cases . And i  want to assign contact user address in cases address.

I have add address field in cases . And i  want to assign contact user address in cases address.

See if using populate_list works in your scenario. André Lopes has several posts in the Community about the use of populate_list. Check them out! :)

Contacts or User's address to assign to the Case custom field?
There is a Contacts subpanel for Cases module with numerous related contacts there, also there is Assigned To field for the Case, which relates Case record to Sugar User. 
All of them - Contacts and a User, - have addresses, moreover, each of the Contacts related to the Case may have Primary and Alternative addresses.