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Simple Snake Game C++ in Unix

Kew (22)
i found myself stuck with it, i had googled a lot of solution which can't solve mine. A lot of solution is written for window system only.Firstly, how to check the keyboard input without the ENTER key pressed by the user? Anyone please help! i had stuck with this problem for 2 days.

Here is my code.

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//SimpleSnakeGame.cpp
//Date : 30/7/2015

#include <iostream>
#include <cstdlib>
#include <ncurses.h>



bool gameover;
const int width = 20;
const int height = 10;
enum eDirection {STOP = 0, LEFT, RIGHT, UP, DOWN};
eDirection dir;
int x, y, foodx, foody, score;


void setUp();
//1)set the snake at the centre of the map.
//2)set the food position

void draw();
/* 
draw the map:
#########
#  	    #
#########
*/

void input();
//get the input of W, A, S, D from the keyboard.
//make switch case.

void logic();
//1)direction of the snake using W,A,S,D.
//2)Random food position
//3)Eat the food and generate another position.
//4)Hit the wall = GameOver.
//5)Tail of the snake grow when eat the food.



using namespace std;

int main()
{
	srand(time(0));
	setUp();
	while(!gameover)
	{
		draw();	
		input();
		logic();

	}
	
	
	
	return 0;
}

void setUp()
{

	gameover = false;
	dir = STOP;
	x = width/2;
	y = height/2;
	foodx = rand()%width;
	foody = rand()%height;

}

void draw()
{
	system("clear");

	for(int i = 0; i < width; i++)
		cout << "#";
	cout << endl;

	for(int j = 0; j < height; j++)
	{
		for(int i = 0; i <width; i++)
		{
			if(i ==0)
				cout << "#";
			else if(i == width -1)
				cout << "#";
			else if(i == x && j == y)
				cout << "O";
			else if(i == foodx && j == foody)
				cout << "F";
			else
				cout << " ";
		}

		cout << endl;
	}

	for(int i = 0; i < width; i++)
		cout << "#";
	cout << endl;
}


void input()
{

	if(_kbhit())
	{
		switch(getch())
		{
			case 'a':
				dir = LEFT;
				break;
			case 'w':
				dir = UP;
				break;
			case 'd':
				dir = RIGHT;
				break;
			case 's':
				dir = DOWN;
				break;
			case 'x':
				gameover = true;	
		}

	}
}
void logic()
{	
	switch (dir)
	{
		case 'LEFT':
			x --;
			break;
		case 'UP':
			y --;
			break;
		case 'RIGHT':
			x ++;
			break;
		case 'DOWN':
			y ++;
			break;
		default:
			break;			  
	}

	if(x > width || x < 0)
		gameover = true;
	if(y > height || y < 0)
		gameover =true;

	if(x == foodx && y == foody)
	{
		score = score + 10;
		foodx = rand()%width;
		foody = rand()%height;
	}

}
koothkeeper (429)
To handle the keyboard that way, you need to look at the ioctl() function call. Another way is to use the curses library.
dhayden (5798)
The C++ doesn't have a standard way of checking keyboard input so it is likely to be different for each operating system you run on.
koothkeeper (429)
Here is one way:

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#include <unistd.h>
#include <termios.h>

char get1ch()
	{
	char buf = 0;
	
	struct termios old = {0};
	
	if( tcgetattr( 0, &old ) < 0 )
		perror( "tcsetattr()" );
		
	old.c_lflag &= ~ICANON;
	old.c_lflag &= ~ECHO;
	old.c_cc[ VMIN ] = 1;
	old.c_cc[ VTIME ] = 0;
	
	if( tcsetattr( 0, TCSANOW, &old ) < 0 )
		perror( "tcsetattr ICANON" );
		
	if( read( 0, &buf, 1 ) < 0 )
		perror( "read()" );
		
	old.c_lflag |= ICANON;
	old.c_lflag |= ECHO;
	
	if( tcsetattr( 0, TCSADRAIN, &old ) < 0 )
		perror( "tcsetattr ~ICANON" );

	return buf;
	
	}
		/*	get1ch()	*/


Last edited on
ChajusSaib (96)
Here is the way I get input:

kbhit.h

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#ifndef kbhit_h
#define kbhit_h
#include <ncursesw/ncurses.h>

// checks if a key a has been pressed(non-blocking)
int kbhit()
{
    int ch = getch();
    if (ch != ERR) {
        ungetch(ch);
        return 1;
    } else {
        return 2;
    }
}

#endif


file/s used in

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#include "kbhit.h"

int main()
{
	if(kbhit())
	{
	    switch (getch())           // check what key it was and take action
	    {
	        case 'W':
	        case 'w':
	        case KEY_UP:
	            // ...
	            break;
	        case 'A':
	        case 'a':
	        case KEY_LEFT:
	            // ...
	            break;
	        case 'S':
	        case 's':
	        case KEY_DOWN:
	            // ...
	            break;
	        case 'D':
	        case 'd':
	        case KEY_RIGHT:
	            // ...
	            break;
	    }
	}

	return 0;
}


If you are really stuck I could post my snake game that I have created with ncurses though I would suggest you take one step at a time and do it yourself. It is a really fun experience once it is close to being done.
Last edited on
Kew (22)
I tried to copy your code to test it on my macbook.

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#include <iostream>
#include <ncurses.h>

// checks if a key a has been pressed(non-blocking)
int kbhit()
{
    int ch = getch();
    if (ch != ERR) {
        ungetch(ch);
        return 1;
    } else {
        return 2;
    }
}


And it return me this error message
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Undefined symbols for architecture x86_64:
  "_main", referenced from:
     implicit entry/start for main executable
  "_stdscr", referenced from:
      kbhit() in test3-f530cb.o
  "_ungetch", referenced from:
      kbhit() in test3-f530cb.o
  "_wgetch", referenced from:
      kbhit() in test3-f530cb.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)


I don't get it.... Please help
Kew (22)
i still can't solve it, it keep give me the same error message
TheIdeasMan (6817)
Hi,

If you are going to use curses, you can't just put a snippet into your code like that, AFAIK there is a procedure - the system has to be initialised & setup. Read the documentation.

http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/
http://math.hws.edu/orr/s04/cpsc225/curses.html


All I did was Google ncurses c++

Good Luck :+)
Kew (22)
i had solved this problem by change the system into "stty raw"

but here is another problem, i have to keep pressing the same key in order to make it move in same direction.

how do i make it run without keep pressing the same key?

here is the code:

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void input()
{
	system("stty raw");

	char key;
	key = getchar();
	{
		switch(key)
		{
			case 'a':
				dir = LEFT;
				break;
			case 'w':
				dir = UP;
				break;
			case 'd':
				dir = RIGHT;
				break;
			case 's':
				dir = DOWN;
				break;
			case 'x':
				gameover = true;	
		}
	}

	

}
void logic()
{	
	switch (dir)
	{
		case LEFT:
			x --;
			break;
		case UP:
			y --;
			break;
		case RIGHT:
			x ++;
			break;
		case DOWN:
			y ++;
			break;
		default:
			break;			  
	}

	system("stty cooked");
Last edited on
Kew (22)
Any one please help? Thank you
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