optimization Tic Tac Toe Game in C

Question

I'm beginner learner in C and one of the assignments I got was to write a Tic Tac Toe game. I have the game running but every time you place X on O position or vice versa it overwrites it. I would also appreciate comments on optimizing the code, because I'm a beginner and don't know a lot of concepts. Thank you! this is what I've got so far

#include<stdio.h>

void redrawBoard(char array[]);
void markBoard (int x, int o, char array[]);
int checkForWin(char array[]);

int checkForWin(char array[])
{   
int a;
char x = 'X';
char o = 'O';

 if (array[0] == x && array[4] == x && array[8] == x)  // winning cases for x 
    return 1;
 if (array[2] == x && array[4] == x && array[6] == x)
    return 1;
 if (array[0] == x && array[1] == x && array[2] == x)
    return 1;
 if (array[3] == x && array[4] == x && array[5] == x)
    return 1;
 if (array[6] == x && array[7] == x && array[8] == x)
    return 1;
 if (array[0] == x && array[3] == x && array[6] == x)
    return 1;
 if (array[1] == x && array[4] == x && array[7] == x)
    return 1;
 if (array[2] == x && array[5] == x && array[8] == x)
    return 1;

 if (array[1] == x && array[4] == x && array[6] == x && array[8] ==x) //checking for draw with x combinations 1st pattern
    return 3;
 if (array[0] == x && array[2] == x && array[4] == x && array[7] ==x)
    return 3;
 if (array[0] == x && array[4] == x && array[5] == x && array[6] ==x)
    return 3;
 if (array[2] == x && array[3] == x && array[4] == x && array[8] ==x)
    return 3;

 if (array[1] == x && array[4] == x && array[5] == x && array[6] ==x) //checking for draw with x combinations 2nd pattern
    return 3;
 if (array[0] == x && array[4] == x && array[5] == x && array[7] ==x)
    return 3;
 if (array[2] == x && array[3] == x && array[4] == x && array[7] ==x)
    return 3;
 if (array[1] == x && array[3] == x && array[4] == x && array[8] ==x)
    return 3;



 if (array[0] == o && array[4] == o && array[8] == o) //// winning cases for o
    return 2;
 if (array[2] == o && array[4] == o && array[6] == o)
    return 2;
 if (array[0] == o && array[1] == o && array[2] == o)
    return 2;
 if (array[3] == o && array[4] == o && array[5] == o)
    return 2;
 if (array[6] == o && array[7] == o && array[8] == o)
    return 2;
 if (array[0] == o && array[3] == o && array[6] == o)
    return 2;
 if (array[1] == o && array[4] == o && array[7] == o)
    return 2;
 if (array[2] == o && array[5] == o && array[8] == o)
    return 2; 

 if (array[1] == o && array[4] == o && array[6] == o && array[8] == o) //checking for draw with o combinations 1st pattern
    return 3;
 if (array[0] == o && array[2] == o && array[4] == o && array[7] == o)
    return 3;
 if (array[0] == o && array[4] == o && array[5] == o && array[6] == o)
    return 3;
 if (array[2] == o && array[3] == o && array[4] == o && array[8] == o)
    return 3;

 if (array[1] == o && array[4] == o && array[5] == o && array[6] == o) //checking for draw with o combinations 2nd pattern
    return 3;
 if (array[0] == o && array[4] == o && array[5] == o && array[7] == o)
    return 3;
 if (array[2] == o && array[3] == o && array[4] == o && array[7] == o)
    return 3;
 if (array[1] == o && array[3] == o && array[4] == o && array[8] == o)
    return 3;
 


 else
    return 0;

 return(a);
}

 void markBoard (int x, int o, char array[])
{
int i = 0;
char j = 'X';
char k = 'O';

while( x >= 1 && x <= 9) 
{
    array[x - 1] = j;
    redrawBoard(array);
    break;
}
while (o >= 1 && o <= 9)
{
    array[o - 1] = k;
    redrawBoard(array);
    break;
}

}

void redrawBoard(char array[])
{
printf(" Player 1 is X;       Player 2 is O;\n\n");
printf("              |      |        \n");
printf("           %c  |  %c   |  %c    \n",array[0],array[1],array[2]);
printf("        ______|______|______  \n");
printf("              |      |        \n");
printf("           %c  |  %c   |  %c    \n",array[3],array[4],array[5]);
printf("        ______|______|______  \n");
printf("              |      |        \n");
printf("           %c  |  %c   |  %c    \n",array[6],array[7],array[8]);
printf("              |      |        \n");
}

int main()
{
int x;
int o;
char array[9] = {'1', '2','3','4','5','6','7','8','9'};

printf("tic tac toe game\n");
redrawBoard(array);


while (checkForWin(array) == 0)
{
    printf("P1 start \n");
    scanf("%d",&x);
    markBoard(x,o,array);

    printf("P2 go on\n");
    scanf("%d", &o);
    markBoard(x,o,array);
}
if (checkForWin(array) == 1)
    printf("P1 won\n");
if (checkForWin(array) == 2)
    printf("P2 won\n");
if (checkForWin(array) == 3)
    printf("draw \n");
return 0;
}

Answer 1

• The problem you mentioned is that you do not have a test when you already have a value in this cell.

• About optimization:

1. Avoid a lot of if cases . Think about better check for checking who is winner, For example: look at this check:

    char winnerIs(char** Board, int i, int j) { if (Board[i][j] == Board[i][(j+1)%3] && Board[i][j] == Board[i][(j+2)%3]) { // got a column return Board[i][j]; } else if (Board[i][j] == Board[(i+1)%3][j] && Board[i][j] == Board[(i+2)%3][j]) { // got a row return Board[i][j]; } else if (i == j && Board[i][j] == Board[(i+1)%3][(j+1)%3] && Board[i][j] == Board[(i+2)%3][(j+2)%3]) { // got the forward diagonal return Board[i][j]; } else if (i+j == 2 && Board[i][j] == Board[(i+2)%3][(j+1)%3] && Board[i][j] == Board[(i+1)%3][(j+2)%3]) { // got the reverse diagonal return Board[i][j]; } else { // got nothing return 0; }

2. Avoid a lot of printing, Better use one structure for the game, for example a board - which is char board[][] or better char** Board if you want a dynamic game. And print the whole board once.

3. Instead of next code:

    printf("P1 start \n"); scanf("%d",&x); markBoard(x,o,array); printf("P2 go on\n"); scanf("%d", &o); markBoard(x,o,array);

Make something like this:

    int player = 1;
    char row, col; 
    player = (player % 2) ? 1 : 2;
    scanf("%c %c", &row, &col);
    markBoard(row, col, board);

Like that you don't need to duplicate a same code and it is automatic knows each turn, who's turn now.

4. Instead of next code:

    if (checkForWin(array) == 1) printf("P1 won\n"); if (checkForWin(array) == 2) printf("P2 won\n"); if (checkForWin(array) == 3) printf("draw \n");

Connect some conditions, like that:

    if (checkForWin(array) == 1 || checkForWin(array) == 2) {
        printf("Congratulations %c!\n", winner);
    } else {
        printf("Game ends in a draw.\n");
    }

5. To make more "beauty" code, you can added a structs which will manage the whole game, for example:

    typedef struct { int size; int **board; // the board /* scores of all options */ int *rowScores; int *colScores; int topLeftBottomRightDiagonalScores; int topRightBottomLeftDiagonalScores; } Game; typedef struct { // position on the board int x; int y; } Position;

6. Your void markBoard (int x, int o, char array[]) function makes to much iterations to print the whole board. Better create the whole board once and after that run on the whole board.