operator in enum c++

Question

I found this code of a tic tac toe game in c++, but got confused with the side^1 in GetComputerMove function-->randMove = GetWinningMove(board, side ^ 1); If anything raise to the power of one will only be the value itself, why should it be ^1? Cos it gave me an error when I remove ^1 :D Can anyone help me to explain this? Thanks!

enum { NOUGHTS, CROSSES, BORDER, EMPTY };
enum { HUMANWIN, COMPWIN, DRAW };
const int directions[4] = { 1, 7, 6, 8 };
const int ConvertTo49[25] = 
{
    8, 9, 10,11,12,
    15,16,17,18,19,
    22,23,24,25,26,
    29,30,31,32,33,
    36,37,38,39,40
};

int GetWinningMove(int* board, const int side)
{
    int ourMove = -1;
    int winFound = 0;
    int index = 0;

    for (index = 0; index < 25; ++index)
    {
        if (board[ConvertTo49[index]] == EMPTY)
        {
            ourMove = ConvertTo49[index];
            board[ourMove] = side;

            if (FindFourInARow(board, ourMove, side) == 4)
            {
                winFound = 1;
            }
            board[ourMove] = EMPTY;
            if (winFound == 1)
            {
                return ourMove;
            }
            ourMove = -1;
        };
    }
    return ourMove;
}

int GetComputerMove(int* board, const int side)
{
    int index;
    int numFree = 0;
    int availableMoves[25];
    int randMove = 0;

    //Set random number to randomly run a function
    int randFunction = 0;
    randFunction = (rand() % 2);

    //Go for the winning move
    randMove = GetWinningMove(board, side);
    if (randMove != -1)
    {
        return randMove;
    }

    //If random function is 1, stop any winning move from the human
    if (randFunction == 1)
    {
        randMove = GetWinningMove(board, side ^ 1);
        if (randMove != -1)
        {
            return randMove;
        }
    }

    randMove = 0;
    //Loop through all squares and put piece in random place
    for (index = 0; index < 25; ++index)
    {
        if (board[ConvertTo49[index]] == EMPTY)
        {
            availableMoves[numFree++] = ConvertTo49[index];
        };
    }

    randMove = (rand() % numFree);
    return availableMoves[randMove];
}

`^` isn't exponentiation in C++, so everything you surmise when thinking it is, is wrong. See [arithmetic operators here](https://en.cppreference.com/w/cpp/language/operator_arithmetic). — WhozCraig, Dec 13 '20 at 11:44

score 1 · Answer 1 · answered Dec 13 '20 at 11:50

In C++, the ^ operator does not mean exponentiation (or raising to a given power); in fact, there is no exponentiation operator in C++ (you have to use the pow function to do that).

Rather, ^ is the exclusive or operator. In your case, given that side will have a value of either 0 or 1 (representing the machine or the player), the side ^ 1 expression will evaluate to the other value. That is, if side is 1, it will give 0 and, if side is 0, it will give 1.

operator in enum c++

1 Answers1