validate char input


Just starting C++ and programming.Writing a game program as follows

char letter;

cin >> letter;

I have a while loop that allows only e for exit and p for play which works fine. If user enters a, n, and so on they get a cout<< " You must enter e or p."; How ever my program goes whack if they enter jjjj or any string with more than one character. I have tried setw and such to no avail. How can I make my program only except only one character and disregard multiple key strokes?

Thank you for any suggestions.
You could possibly change your while loop to an if loop. For example:
if (letter==e) //exit
else if (letter==p) //play
else //cout statement 

Hopefully the last else statement would take care of the issue.
Here is my code, I tried your suggestion but if I entered rr or dhfu or anything except a single character the game starts playing itself over and over again at light speed. What I need is a way to only accept one key stroke if user enters more than one. Thanks

char letter;// To hold cin value.

while (letter != 'e')//while loop.

cout << " This is a dice game that you play with the computer as your opponent.\n";
cout<< " The highest total resulting from a roll of two dice wins the game!!\n\n";
cout << " Press r to roll the dice or e to exit the game, then press enter. ";
cin >>letter;

srand((unsigned)time(0)); //Initialize random number generator (not sure if I am using this correctly).

//Random number generator
playerDice1 = (rand() % 6) + 1;
playerDice2 = (rand() % 6) + 1;
compDice1 = (rand() % 6) + 1;
compDice2 = (rand() % 6) + 1;

if (letter == 'e')// An if statement, player enters e the program terminates.
if (letter != 'r')/* An if Statement, player enters anything except p a heckling message
is displayed and computer beeps 3 times. Player enters p the program continues*/
i tried it nothing i think that this "while (letter != 'e')//while loop." is wrong you could put "while (letter==e) //exit'//while loop."why dont use this i think
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