Bounce around screen

[Akilla]

How do I bounce a star around the screen using gotoxy ?

I tried the follwing but it doesn't work after sometime:

#include <stdio.h>
#include <conio.h>
#include <dos.h>

struct gamecomponent
{
    int bufx, bufy;
    int oldx, oldy;
    int newx, newy;
    int speed;
    //void resetcoords();
} ball, paddle;

void gamecomponent :: resetcoords()
{
    oldx = bufx;
    oldy = bufy;
    bufx = newx;
    bufy = newy;
}

void changecoordball()
{
    int xadd, yadd, depvar=0;

    if (ball.newx >= 80)
    {
        xadd = -ball.speed;
        depvar = 1;
    }

    if (ball.newx <= 0)
    {
        xadd = ball.speed;
        depvar = 1;
    }

    if (ball.newy >= 25)
    {
        yadd = -ball.speed;
        depvar = 1;
    }

    if (ball.newy <= 0)
    {
        yadd = ball.speed;
        depvar = 1;
    }

    if (ball.newy == paddle.newy)
    {
        if (ball.newx >= paddle.newx && ball.newx <= (paddle.newx + 3))
        {
            xadd = -ball.speed;
            depvar = 1;
        }

        if (ball.newx > (paddle.newx + 3) && ball.newx <= (paddle.newx + 7))
        {
            xadd = ball.speed;
            depvar = 1;
        }
    }

    if (depvar != 1)
    {
        xadd = 1;
        yadd = 1;
    }

    ball.newx = ball.newx + xadd;
    ball.newy = ball.newy + yadd;
}

void changecoordpaddle(int direction)
{
    int delx;

    if (direction == 1)
    {
        delx = paddle.speed;
    }
    else
    {
        delx = -paddle.speed;
    }

    paddle.newx = paddle.newx + delx;
}

void initialize()
{
    ball.bufx = 1;
    ball.bufy = 1;
    ball.newx = 1;
    ball.newy = 1;
    ball.oldx = 1;
    ball.oldy = 1;
    ball.speed = 2;

    paddle.bufx = 1;
    paddle.bufy = 25;
    paddle.newx = 1;
    paddle.newy = 25;
    paddle.oldx = 1;
    paddle.oldy = 25;
    paddle.speed = 1;
}

void placeball()
{
    gotoxy(ball.oldx, ball.oldy);
    printf(" ");
    gotoxy(ball.newx, ball.newy);
    printf("*");
}

void placepaddle()
{
    gotoxy(paddle.oldx, paddle.oldy);
    printf("       ");
    gotoxy(paddle.newx, paddle.newy);
    printf("=======");
}

int checkbounce()
{
    int bounceval = 1;

    if (ball.newy == paddle.newy)
    {
        if (ball.newx < paddle.newx || ball.newx > (paddle.newx + 7))
        {
            bounceval = 0;
        }
    }

    return bounceval;
}


main()
{
    clrscr();
    initialize();

    while (1 == 1)
    {
        changecoordball();
        resetcoordsball();
        placeball();
        delay(100);
        while (kbhit())
        {
            return 0;
        }
    }
    
} 

Any help is appreciated.

COOL PROGRAMS @ www.akilla.tk