Using an if statement for multiple conditions

[WowICantProgram]

I'm trying to make a small guessing game where the user isn't allowed to guess the same number twice. Is there a way to shorten this?

    if (x == a || x == b || x == c || x == d){
        exit(0);}
//a, b, c, and d are past user inputs. x is the current input 

I'm pretty sure that using a while loop would be better in this case. I'm just wondering if there's a shorter way to write my if statement.

[Codermik]

Store you guesses in an array or vector, and just loop through and check whatever the user entered isn't already there.

[Codermik]

Something like this...

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#include <iostream> const int MAX_GUESSES = 10; bool checkGuess(char guesses[], char guess) { // for info, static ensures that count // retains its value when we leave the // function.. normally each time we call // the function it would be set to 0. static int count = 0; // loop through the array to see if // whatever is in guess is already // there.. return true if it is. for (int i = 0; i < MAX_GUESSES; i++) if (guesses[i] == guess) return true; // not there so store it and return false guesses[count] = guess; count++; return false; } int main() { // storage for my guesses, and guess char myGuessList[MAX_GUESSES] = { 0 }; char guess; for (int i = 0; i < MAX_GUESSES; i++) { // grab guess std::cout << "Enter Guess: "; std::cin >> guess; // check quess. if (checkGuess(myGuessList, guess)) std::cout << "You tried " << guess << "!" << std::endl; { // it wasnt already there so do something with it.. } } return 0; }

Enter Guess: A Enter Guess: B Enter Guess: C Enter Guess: A You tried A!

[andywestken]

I would probably follow the same kind of approach, but use a more generic function than Softrix's checkGuess(), e.g.

// generic search function -- can be used elsewhere
// adjust type to suit
int findInArray(int arr[], int size, int val) {
    for (int i = 0; i < size; i++) {
        if (arr[i] == val)
            return i;
    }
    return -1; // means not found by convention
}

then, where myGuessList is an array, MAX_GUESSES is the size of the array, and guess is a variable set to the value of the latest guess, ...

        if (-1 == findInArray(myGuessList, MAX_GUESSES, guess))
        {
            // it not found in list...
            // TODO implementation
        }
        else
        {
            std::cout << "You've already tried " << guess << "!\n";
        }

Note that you should aim to avoid global (aside from common consts) and static variables if at all possible!!

Andy

PS I assume you're writing your guessing game to learn C++, so the suggested solutions are the kind of thing you should go for.

But if you were wanting to write your game as succintly as possible then you'd use the standard C++ containers and algorithms. If you don't care what order the user guessed the numbers in, the best bet would probably be std::set.
http://www.cplusplus.com/reference/set/set/