How can i call a function which is usually used by root?

["wk" <304702903 qq com>]

I want write a c program.And a common user(not in root group) will run this program.
In this program,I call fread(/dev/sdc...) and fwrite(/dev/sdc),but this
call will return "permission no allow".If I use the root user,will be
ok.
How to change to the authority to root's?

I know the  root's password.