Week 1 solved question: change environment by shell

How to change environment by using a shell?

e.g. 

For this laboratory we assume you're in the standard C or POSIX locale. The shell command locale should output LC_CTYPE="C" orLC_CTYPE="POSIX". If it doesn't, use the following shell command:

export LC_ALL='C'

If I write a shell that contains this command, it won't work since the child shell only change it's own environment. 

I need to use:

. ./shellname  or

source ./shellname