Text modifying script

[Agrajag]

i would like a simple PHP script which replaces all underscores in a string with spaces. i have no idea of how to go about writing such a script
this will be used in a php page which includes other php or html pages into it which are defined by a query string. the name of the page will be turned into a title by means of this script.

Please help!
thanks

[Twey]

$title = str_replace("_", " ", $url); 

[Agrajag]

Wow thanks that's so easy