sorry for the ambiguious title!

I want to to write some logic that says if this file array has this name then do this.....what i mean is if someone has selected a file from their hard drive in to a file upload box with a name attribute of 'file_field' and uploaded the file how do i say in my script at the other end.....if the file array is called 'file_field' then do this....

ive tried if($_FILES == 'field')

But it doesnt work!

any ideas?