Htykuut

(program language is c - when correcting please only use stuff noobs can do, I am just learning this since 1 week)

The problem is: See the "int snakelen = 1;" at the start of main?

I never change that integer. But when I end the game it is 0. Why?

And if i TRY TO CHANGE snakelen mid-game, the game completely breaks and i get windows-error sounds.
What's the matter?

(And the food doesnt spawn randomly although i use a randomizer. And it either spawns bottom-only or top-only - changing about every 5 minutes. another wierd glitch.)

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <conio.h>

#include <time.h>

#include <math.h>



#define SIZE 2048 //32(*2 because every 2nd one is a space) * 32

#define HSIZE 1024 //32 * 32

#define UP_ 1

#define DOWN_ 3

#define LEFT_ 4

#define RIGHT_ 2

#define YSIZE 64 //length of a row (including spaces)



//TO PLAY: Start the game once, right-click the command-promt at the top, click Settings -> Layout . Then change the window size to 64 (hor) * 33 (vert)



int counter = 0;

int gamespeed = 400;//Intervall in which a game-frame gets rendered



int spawnfood(int* freetable, int snakelen)

{

    srand ( time(NULL) ); //randomize

    int randomIndex = rand()%(HSIZE - 1); //take random non-x-filled position from array

    int randomValue = freetable[randomIndex]; //output the random position

    return randomValue;

}



int main()

{

    int nofood = 1; //is there food in the game? 1 = no

    //int tmp = 0; //temporary memory for later

    int tmp2 = 0; //temporary memory2

    int snakelen = 1; //length of snake

    int snakedir = RIGHT_; //Position the snake is looking

    int snakeheadxpos = 0; //x-position of snake

    int snakeheadypos = 0; //y-position of snake

    char q;//The button that was pressed last





    char gametable[SIZE]; //the game-screen //fill it with spaces

    for(int i = 0; i < SIZE; i++)

    {

        gametable[i]=' ';

    }

    gametable[SIZE] = '';





    int freetable[(HSIZE)]; // 32*32 list of all pixels, which shows whether a pixel is an x or not

    for(int i = 0; i < (HSIZE); i++)

    {

        freetable[i]= i*2; //fill the array with its numbers

    }





    //START OF GAME

    printf("Press any Button to start the game!n");

    getch();

    for(int i = 0; i < 31; i++){

        printf("n");

    }



    while(q != 27)

    {

        counter++;

        if(kbhit()) //if button is pressed

        {

            q = getch(); //q = that button

            switch(q) //change the way the snake looks via WASD

            {

            case 'w':

                if(snakedir != DOWN_)

                    snakedir = UP_;

                break;

            case 'a':

                if(snakedir != RIGHT_)

                    snakedir = LEFT_;

                break;

            case 's':

                if(snakedir != UP_)

                    snakedir = DOWN_;

                break;

            case 'd':

                if(snakedir != LEFT_)

                    snakedir = RIGHT_;

                break;

            default:

                break;

            }



        }

        if(counter%gamespeed == 0) //Renders a game-frame at the intervall of gamespeed

        {

            switch(snakedir)

            {



            case UP_:

                if(snakeheadypos==0)

                {

                    goto exit_loop; //ran into a wall

                }

                snakeheadypos--;

                break;



            case DOWN_:

                if(snakeheadypos==31)

                {

                    goto exit_loop; //ran into a wall

                }

                snakeheadypos++;

                break;



            case RIGHT_:

                if(snakeheadxpos==31)

                {

                    goto exit_loop; //ran into a wall

                }

                snakeheadxpos++;

                break;



            case LEFT_:

                if(snakeheadxpos==0)

                {

                    goto exit_loop; //ran into a wall

                }

                snakeheadxpos--;

                break;

            default:

                break;

            }



            if((gametable[snakeheadypos*YSIZE + 2*snakeheadxpos] == 'o'))

            {

                //snakelen++; //<-- WHEN YOU REMOVE THE FIRST //, THE GAME STARTS TO BUG AND I GET WINDOWS ERROR SOUNDS!

                nofood = 1; //no more food is in the game

            }

            gametable[snakeheadypos*YSIZE + 2*snakeheadxpos] = 'x'; //set the pixel ur at the the moment to 'x'



            gametable[tmp2] =' ';

            tmp2 = snakeheadypos*64+snakeheadxpos*2;

            //spawn food if there is none

            if(nofood)

            {

                gametable[spawnfood(freetable, snakelen)] = 'o';

                nofood = 0; //food is already placed

            }

            printf("%s", gametable); // print the gametable

        }

    }

exit_loop: ; //if you ran into a wall

    printf("Game Over - Score: %d", snakelen);

}

 char gametable[SIZE]; //the game-screen //fill it with spaces

 ...

 gametable[SIZE] = '';

This is wrong. You can index an array of size N with indices 0 through N-1. gametable[SIZE] is outside the array, and assigning to it invokes undefined behavior.

Caveat: This isn't a "give a man a fish" answer. It's a "teach a man to fish' answer.

On every one of your statements that reads or writes to an array, you should check the array index for validity.

For example, instead of

gametable[snakeheadypos*YSIZE + 2*snakeheadxpos] = 'x';



gametable[tmp2] =' ';

...write...

int index;



index=snakeheadypos*YSIZE + 2*snakeheadxpos;

if(index<0 || index >=SIZE){printf("Index error A: value is %d", index);exit(1);}

gametable[index] = 'x';



index=tmp2;

if(index<0 || index >=SIZE){printf("Index error B: value is %d", index);exit(1);}

gametable[index] =' ';

This sort of technique can help you detect array index problems, which can be a very common source of bugs, and can produce all sort of weird symptoms.