Any shortened version of this code?

[DoomyNY]

Is there any way to shorten the while loop? Maybe through use of an array or maybe something in the C++ library?

char choice; 
while (choice != 'a' && choice != 'b'&& choice != 'c' && choice !='d' )

[AbstractionAnon]

while (choice < 'a' || choice > 'd' )  

[DoomyNY]

That's so simple. I cant believe I didn't think of that! Thanks.