a simple C version of the popular 2048 game

2048.c

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <termios.h>
#include <unistd.h>

#define SIZE 4

struct game {
	int tiles[SIZE][SIZE];
};

enum {
	DOWN,
	UP,
	LEFT,
	RIGHT,
	MOVES
};

int random_spot(struct game* g)
{
	return rand() % SIZE;
}

int random_value(struct game* g)
{
	return (rand() % 10) ? 2 : 4;
}

void print(struct game* g)
{
	int i,j;
	printf("--------------------------\n");
	for (j = SIZE - 1; j >= 0; --j) {
		printf("|");
		for (i = 0; i < SIZE; ++i) {
			if (g->tiles[i][j])
				printf("%4d  ", g->tiles[i][j]);
			else
				printf("      ");
		}
		printf("|\n");
	}
	printf("--------------------------\n");
}

void twist(struct game* g)
{
	int i,j;
	struct game g2;
	for (i = 0; i < SIZE; ++i)
	for (j = 0; j < SIZE; ++j)
		g2.tiles[i][j] = g->tiles[j][i];
	*g = g2;
}

void flip(struct game* g)
{
	int i,j;
	struct game g2;
	for (i = 0; i < SIZE; ++i)
	for (j = 0; j < SIZE; ++j)
		g2.tiles[i][j] = g->tiles[i][SIZE - j - 1];
	*g = g2;
}

void begin(struct game* g)
{
	struct game g2 = {};
	*g = g2;
	g->tiles[random_spot(g)][random_spot(g)] = random_value(g);
	g->tiles[random_spot(g)][random_spot(g)] = random_value(g);
}

void fall_column(int* a, int* b)
{
	int i,j;
	int prev = 0;
	j = 0;
	for (i = 0; i < SIZE; ++i)
		if (a[i]) {
			if (a[i] == prev) {
				b[j - 1] *= 2;
				prev = 0;
			} else {
				b[j++] = a[i];
				prev = a[i];
			}
		}
}

void fall(struct game* g)
{
	struct game g2 = {};
	int i;
	for (i = 0; i < SIZE; ++i)
		fall_column(g->tiles[i], g2.tiles[i]);
	*g = g2;
}

int same(struct game* a, struct game* b)
{
	int i,j;
	for (i = 0; i < SIZE; ++i)
	for (j = 0; j < SIZE; ++j)
		if (a->tiles[i][j] != b->tiles[i][j])
			return 0;
	return 1;
}

int tryfalling(struct game* g)
{
	struct game g2 = *g;
	fall(g);
	if (same(g, &g2))
		return 0;
	return 1;
}

void popup(struct game* g)
{
	int i,j;
	while (1) {
		i = random_spot(g);
		j = random_spot(g);
		if (!g->tiles[i][j]) {
			g->tiles[i][j] = random_value(g);
			return;
		}
	}
}

void move(struct game* g, int way)
{
	if (way / 2)
		twist(g);
	if (way % 2)
		flip(g);
	if (tryfalling(g))
		popup(g);
	if (way % 2)
		flip(g);
	if (way / 2)
		twist(g);
}

int read_move(void)
{
	char keys[MOVES] = {'k','i','j','l'};
	int c;
	int i;
	while (isspace(c = getchar()));
	if (c == EOF)
		return c;
	for (i = 0; i < MOVES; ++i)
		if (c == keys[i])
			return i;
	return EOF;
}

static struct termios backup;
static struct termios current;

void take_stdin(void)
{
	tcgetattr(STDIN_FILENO, &backup);
	current = backup;
	current.c_lflag &= (~ICANON & ~ECHO);
	tcsetattr(STDIN_FILENO, TCSANOW, &current);
}

void give_stdin(void)
{
	tcsetattr(STDIN_FILENO, TCSANOW, &backup);
}

int main()
{
	int c;
	struct game g;
	begin(&g);
	print(&g);
	take_stdin();
	while ((c = read_move()) != EOF) {
		move(&g, c);
		print(&g);
	}
	give_stdin();
	return 0;
}

Is this code working?

no

The code works, but is a pretty primitive