Do-While loop executing again at false condition

Unreal Courses Talk
,
#1

Briefing: I have put a check of users valid input if he wants to play again or not. On selecting Y, the game restarts. On selecting N the game ends. But on selecting W (any other option) the game asks again for valid selection from Y or N. But this time if user selects N the game restarts. Where as the game should have ended.
Bug regeneration steps:

  1. Start the Game
  2. Enter abcd and press enter (do this 5 times in total)
  3. Enter W press enter (Game will ask again for valid input from Y or N)
  4. Enter N [bug: Logical error. The game should have ended but rather it starts again.]

Code snippet:
bool AskToPlayAgain(); //Function prototype

//Entry point
int main()
{
do {
PrintIntro();
PlayGame();
} while (AskToPlayAgain()); //AskToPlayAgain() returning true where it should return false as per the steps
return 0;
}

bool AskToPlayAgain() //Method definition
{
std::string playAgain = “”;
std::cout << "Do you want to play again? [Y/N]: ";
std::getline(std::cin,playAgain);
if (playAgain[0] == ‘y’ || playAgain[0] == ‘Y’)
{
return true;
}
else if (playAgain[0] == ‘n’ || playAgain[0] == ‘N’)
{
return false;
}
else
{
std::cout << “\nWrong input. Please enter again\n.”;
AskToPlayAgain();
}
}

Project Link:
BullCowGame.zip (241.6 KB)

Please let me know why is it happening?

#2

Think about what’s happening when you call AskToPlayAgain in the else statement, what’s going to happen with the returned value.

#3

Is it related to stack? Its a recursive function so, while popping, does it pops the return values backwords?

#4

Does this illustrate the issue?

main
|-AskToPlayAgain()
 |- AskToPlayAgain() // --return true to caller ^

else
{
    std::cout << “\nWrong input. Please enter again\n.”;
    true;
}

If you can’t figure it out:

else
{
    std::cout << “\nWrong input. Please enter again\n.”;
    return AskToPlayAgain();
}
#5

main
|-AskToPlayAgain()
|- AskToPlayAgain() // --return true to caller ^

This is the issue that it returns true to the caller, which is a condition for do-while iteration. Hence it iterates again. I tried debugging. In watch window I see AskToPlayAgain() fuction returning false and below that AskToPlayAgain() funtion returning true.

#6

"which is a condition for do-while iteration"
Only the first instance, look where the recursive calls are returning the value to (see code I provided above)

Privacy & Terms