tateti_from_scratch

this is an implementation of ta-te-ti (tic-tac-toe) inc, made from scratch just for fun

game rules (ta-te-ti)

• we have a board with a 3x3 grid.
• there are two players, one uses X and the other uses O
• on each turn, a player choose an empty cell and place his mark.
• the first player to get three in a row (horizontally, vertically or diagonally) wins.
• if all 9 cells are filled and nobody has a line of three points, the game is a draw.
• palyers cannot overwrite an occupied cell.
• the game ends when someone wins or when the board is full.

modeling the game in c

board

3x3 array of cells. each cell is EMPTY, X or O.

typedef enum {EMPTY=0, X=1, O=2} Cell;

players

current player is either X or O.

game status

can be IN_PROGRESS, X_WON, Y_WON or DRAW.

typedef enum {IN_PROGRESS, X_WON, O_WON, DRAW} State;

game

all info of the game it's contained on a struct:

typedef struct {
    Cell board [3][3]; // bi-dimensional array of 3x3 cells
    Cell current;      // X or O
    State state;
} Game;

movements

place a X or O in a pair (row, column) that can be 0, 1 or 3.

short move(Game* game, short row, short column); // return 0 if success, 1 if its a illegal movement

after of each movement, the state is evaluated and updated.

game loop

init a game

while (state == IN_PROGRESS)
    update_board();
    
    do
    ask current player for a next movement (row, column)
    while (movement = invalid)
    
    place mark
    evaluate and update state
    
update_board();

print results (based on current state)

how to run

compile

gcc -o tateti main.c

run

./tateti

notes

• input format: row, column or row column (int)
• invalid inputs are handled by asking again
• next improvements
  • input by a single number (1-9) mapped to coordinates
  • single-player mode with "ai"
  • better board display