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POUsing a pointer to dynamically allocate array
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2013-04-15T14:52:34.367
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<p>I am trying to use a dynamically allocate an array using a pointer in my tic tac toe game. I am a little confused on how exactly pointers work. We are using the cplusplus.com website as our textbook, and I think the section on pointers is a little confusing for me. Would it be possible to get a explanation of it and possibly help do that to my tic tac toe game? Here is my code:</p> <pre><code>//Sophia Ali // TicTacToe (CS-509 Assignment 5) #include<iostream> #include<cstdlib> using namespace std; enum Status { WIN, DRAW, CONTINUE, QUIT }; void showBoard( const char board[], int boardSize ); // show current state of board Status checkGameState( const char board[] ); // returns WIN or CONTINUE int getHumanSquare( const char board[] ); int getComputerSquare( const char board[] ); bool checkBadSquare( const char board[], int squareNum ); // checks to see if a chosen square is already taken; returns true if // already taken; used by get*Square functions above. int getrandint( int min, int max ); int main() { char board[] = "123456789"; // 10 element char board const int boardSize = 10; Status gameState = CONTINUE; int gametype, squareChoice, turnNum = 0; char currentSymbol; // 'o' or 'x' cout << "\n This is a Tic Tac Toe program. Choose the type of game: " << "\n (1) human o vs. human x (2) human o vs. dumb computer x" << "\n\n -> "; cin >> gametype; /* Show the current state of Tic Tac Toe board. */ showBoard( board, boardSize ); /* Main game loop */ while ( gameState == CONTINUE ) { /* Increment turnNum by 1. */ turnNum++; /* If turnNum equal to 10 Set gameState to DRAW. Break out of while loop. */ if ( turnNum == 10 ) { gameState = DRAW; break; } /* If we are on an odd-numbered turn Print "It's o's turn." Set currentSymbol to 'o'. Call getHumanSquare function to get squareChoice. Else (we are on an even-numbered turn) Print "It's x's turn." Set currentSymbol to 'x'. If the gametype is 1 (human vs. human) Call getHumanSquare function to get squareChoice. Else (gametype is 2 (human vs. computer)) Call getComputerSquare function to get squareChoice.*/ // Get current player's square choice and insert into board if ( turnNum%2 != 0) { cout << "\n It's o's turn."; currentSymbol = 'o'; squareChoice = getHumanSquare( board ); } else { cout << "\n It's x's turn."; currentSymbol = 'x'; if ( gametype == 1 ) squareChoice = getHumanSquare( board ); else squareChoice = getComputerSquare( board ); } /* If squareChoice is -1 (human player quit) Set gameState to QUIT. Else Insert currentSymbol into board at (squareChoice - 1). Show the current state of the Tic Tac Toe board. Call checkGameState function to determine the gameState. */ if ( squareChoice == -1 ) gameState = QUIT; else { board[ squareChoice - 1 ] = currentSymbol; showBoard( board, boardSize ); gameState = checkGameState( board ); } } // end while /* If gameState is WIN print "Player " currentSymbol " is the winner." */ /* If gameState is DRAW print "It's a draw." */ if ( gameState == WIN ) cout << "Player " <<currentSymbol << " is the winner."; if ( gameState == DRAW ) cout << "It's a draw."; return 0; } // end main ///////////////////////////////////////////////////////////////////// void showBoard( const char board [], int size ) { cout << endl; for ( int i = 0; i < size ; i++ ) { cout << board[ i ] << " "; if ( ( i + 1 ) % 3 == 0 ) cout << endl; } cout << endl; } ///////////////////////////////////////////////////////////////////// Status checkGameState( const char board[] ) { // Board Array // // 1 2 3 0 1 2 // 4 5 6 --> 3 4 5 // 7 8 9 6 7 8 // // Diagonal winners if ( board[ 0 ] == board[ 4 ] && board[ 0 ] == board[ 8 ] ) return WIN; else if ( board[ 2 ] == board[ 4 ] && board[ 4 ] == board[ 6 ] ) return WIN; // Horizontal winners else if ( board[ 0 ] == board[ 1 ] && board[ 1 ] == board[ 2 ] ) return WIN; else if ( board[ 3 ] == board[ 4 ] && board[ 4 ] == board[ 5 ] ) return WIN; else if ( board[ 6 ] == board[ 7 ] && board[ 7 ] == board[ 8 ] ) return WIN; // Vertical winners else if ( board[ 0 ] == board[ 3 ] && board[ 3 ] == board[ 6 ] ) return WIN; else if ( board[ 1 ] == board[ 4 ] && board[ 4 ] == board[ 7 ] ) return WIN; else if ( board[ 2 ] == board[ 5 ] && board[ 5 ] == board[ 8 ] ) return WIN; else return CONTINUE; } ///////////////////////////////////////////////////////////////////// int getHumanSquare( const char board[] ) { int squareNum; cout << "\n Input the number of an empty square: (-1 to quit) "; cin >> squareNum; while ( checkBadSquare( board, squareNum ) == true ) { cout << "\n Bad input. Choose another square: "; cin >> squareNum; } return squareNum; } ///////////////////////////////////////////////////////////////////// int getComputerSquare( const char board[] ) { int squareNum; squareNum = getrandint( 1, 9 ); while ( checkBadSquare( board, squareNum ) == true ) { squareNum = getrandint( 1, 9 ); } return squareNum; } ///////////////////////////////////////////////////////////////////// bool checkBadSquare( const char board[], int squareNum ) { int realSquareNum = squareNum - 1; // count from 0 if ( squareNum == -1 ) return false; // Let quit code pass as a valid square else if ( squareNum > 9 ) return true; // Square numbers out of range are invalid else if ( board[ realSquareNum ] == 'o' || board[ realSquareNum ] == 'x' ) return true; // Occupied squares are invalid else return false; // Valid square number } ///////////////////////////////////////////////////////////////////// int getrandint( int min, int max ) { int scale, shift; scale = max - min + 1; shift = min; return rand() % scale + shift; } </code></pre>
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<c++><pointers><dynamic-allocation>
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Using a pointer to dynamically allocate array
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