Display a field onlt up to a Specific Character

Hi
Can someone please tell me if there is a function that can be used to print a field only up till a specific character. For ex: I'm trying to print all the student email Id's bu only the characters that fall before the "@." sign.
Thanks
ACleft(x, instr(x, '@.') -1)|||Hello
Thank you sooo much. It worked!!

Thanks again
Aparna