#include <time.h>
#include <iostream>
#include <string>
#include <iomanip>
#include <cstdlib>
//using this to avoid repeating
typedef unsigned int uint;
using namespace std;
//directions enumerations
enum movDir { UP, DOWN, LEFT, RIGHT };
class tile
{
public:
tile() : val( 0 ), blocked( false ) {}
//unsigned integer
uint val;
bool blocked;
};
// Board, winning and losing, control keys,
class g2048
{
public:
//we're not done, no one's won, score's 0 and we are gonna move
g2048() : done( false ), win( false ), moved( true ), score( 0 ) {}
//function loop
void loop()
{
addTile();
while( true )
{
if( moved )
addTile();
drawBoard();
if( done )
break;
ControlKey();
}
string s = "Game Over!";
if( win ) s = "You made it!";
cout << s << endl << endl;
} //end of func loop
private:
//This is how the board looks like
void drawBoard()
{string
system( "cls" );
cout << "SCORE: " << score << endl << endl;
for( int y = 0 ; y < 4 ; y++ )
{
cout << "+------+------+------+------+" << endl << "| ";
for( int x = 0; x < 4; x++ )
{
if( !board[x][y].val )
//setw is to add in spaces in each box
cout << setw( 4 ) << " ";
else
cout << setw( 4 ) << board[x][y].val;
cout << " | ";
}
cout << endl;
}
cout << "+------+------+------+------+" << endl << endl;
}
void ControlKey()
{
moved = false;
char c;
//Control Keys
cout << "(W)Up (S)Down (A)Left (D)Right ";
cin >> c;
/* Bitwise AND, the individual bits of c will be ANDed with
the corresponding bits of the hex number 0x5F.
This is a bitmasking, so the bit 5 of c gets cleared, while bits
0 to 4 and 6 remain untouched. (all higher order bits will be cleared)
*/
c &= 0x5F;
switch ( c )
{
case 'W': move( UP );
break;
case 'A': move( LEFT );
break;
case 'S': move( DOWN );
break;
case 'D': move( RIGHT );
}
// can you still move?
for( int y = 0; y < 4; y++ )
for( int x = 0; x < 4; x++ )
board[x][y].blocked = false;
}
void addTile()
{
for( int y = 0; y < 4; y++ )
for( int x = 0; x < 4; x++ )
//if board is not empty
if( !board[x][y].val )
{
uint a, b;
do
{
//rand() standard lib func that generates rand #
a = rand() % 4;
b = rand() % 4;
}
while( board[a][b].val );
int s = rand() % 100;
if( s > 89 ) board[a][b].val = 4;
else board[a][b].val = 2;
if( canMove() )
return;
}
done = true;
}
bool canMove()
{
for( int y = 0; y < 4; y++ )
for( int x = 0; x < 4; x++ )
//if the board's empty, you can move
if( !board[x][y].val )
return true;
for( int y = 0; y < 4; y++ )
for( int x = 0; x < 4; x++ )
{
if( testAdd( x + 1, y, board[x][y].val ) )
return true;
if( testAdd( x - 1, y, board[x][y].val ) )
return true;
if( testAdd( x, y + 1, board[x][y].val ) )
return true;
if( testAdd( x, y - 1, board[x][y].val ) )
return true;
}
return false;
}
//v is the board[x][y].val
bool testAdd( int x, int y, uint v )
{
//out of range
if( x < 0 || x > 3 || y < 0 || y > 3 )
return false;
return board[x][y].val == v;
}
// Verticall movement (Up, Down)
void moveVert( int x, int y, int d )
{
if( board[x][y + d].val && board[x][y + d].val == board[x][y].val && !board[x][y].blocked && !board[x][y + d].blocked )
{
board[x][y].val = 0;
board[x][y + d].val *= 2;
//update score
score += board[x][y + d].val;
board[x][y + d].blocked = true;
moved = true;
}
else if( !board[x][y + d].val && board[x][y].val )
{
board[x][y + d].val = board[x][y].val;
board[x][y].val = 0;
moved = true;
}
if( d > 0 ) {
if( y + d < 3 )
moveVert( x, y + d, 1 );
}
else {
if( y + d > 0 )
moveVert( x, y + d, -1 );
}
}
//Horizontal movement (Right, Left)
void moveHori( int x, int y, int d )
{
if( board[x + d][y].val && board[x + d][y].val == board[x][y].val
&& !board[x][y].blocked && !board[x + d][y].blocked )
{
board[x][y].val = 0;
board[x + d][y].val *= 2;
//update score
score += board[x + d][y].val;
board[x + d][y].blocked = true;
moved = true;
}
else if( !board[x + d][y].val && board[x][y].val )
{
board[x + d][y].val = board[x][y].val;
board[x][y].val = 0;
moved = true;
}
if( d > 0 ) {
if( x + d < 3 )
moveHori( x + d, y, 1 );
}
else {
if( x + d > 0 )
moveHori( x + d, y, -1 );
}
}
void move( movDir d )
{
switch( d )
{
case UP:
for( int x = 0; x < 4; x++ )
{
int y = 1;
while( y < 4 )
{
if( board[x][y].val )
moveVert( x, y, -1 );
y++;
}
}
break;
case DOWN:
for( int x = 0; x < 4; x++ )
{
int y = 2;
while( y >= 0 )
{
if( board[x][y].val )
moveVert( x, y, 1 );
y--;
}
}
break;
case LEFT:
for( int y = 0; y < 4; y++ )
{
int x = 1;
while( x < 4 )
{
if( board[x][y].val )
moveHori( x, y, -1 );
x++;
}
}
break;
case RIGHT:
for( int y = 0; y < 4; y++ )
{
int x = 2;
while( x >= 0 )
{
if( board[x][y].val )
moveHori( x, y, 1 );
x--;
}
}
}
}
tile board[4][4];
bool win, done, moved;
uint score;
};
int main()
{
//srand() std lib func, seeding a rand num generator
//return val of unsigned int time() ---> random value
srand( static_cast <uint>( time( NULL ) ) );
g2048 g;
g.loop();
return system( "pause" );
}
Without the c &= 0x5F it would just keep drawing the board without any changes made to it. What does this line do? This is the 2048 game. I think this part of the code is trying to AND this Bitwise, but I don't really understand the mechanism. What exactly happens that makes the simple line so important that without it, everything's wrong?
