I'm trying to code a program to read the user's input and have it:

-count vowels
-stop counting vowels after '.' or '?' (ie. abcdjwef is 1 a, 1 e; while fje.fwdfeiii is just 1 e)
-closes when ENTER is pressed after a '.' or '?' is found (ie. closes after 'abacds. ENTER' as well as 'as.fefsdf ENTER')
-display the number of vowels

Is there any way to do this with only 'cin >> userInput' and a while loop checking for punctuation?