Limiting number of characters to be displayed in recent posts ( headline)

Hello, I am rtruing to display the recent post. Here is the code i used to display the recent posts in my template.

` <?php get_archives(‘postbypost’, 4); ?>

it gives this rsult

Recent Posts

* Recent discovery shows new ways to fight cancer
* Obama blasts “quasi-incumbent” Clinton
* The Great iPhone Hack, round 3
* FACTBOX-Iraq and economy hold keys to Australian election

I want each headline to, display certain number of characters ( in this case 22 character )and headline ending with two dots .

Then it must look like this

Recent Posts

* Recent discovery shows..
* Obama blasts “quasi-in..
* The Great iPhone Hack,..
* FACTBOX-Iraq and econo..

Any help will be appreciated. Thnak you