What's wrong with these two classes? How to draw a line and move it in C++, using class “line”and class “point”?

Question

I have two classes, line and point. So far, in point.cpp, I have setpoint, drawpoint, erasepoint, and movepoint (with char as an input). Now, in line.cpp, I need to have setline, drawline, and moveline. My problem is: Point only moves once in the direction I choose, and line won't draw at all.

In point.cpp:

void point::setpoint(int a, int b, int col, char c)
{
    X = a;
    Y = b;
    Character = c;
    Color = col;
}

void point::draw()
{
    gotoxy(X, Y);
    color(Color);
    cout << Character;
}

void point::erase()
{
    gotoxy(X, Y);
    cout << " ";
}

void point::move(char dir)
{
    erase();
    dir = getch();
    if(dir == '/')
    {
        X--;
        Y--;
    }
    else if(dir == 'a' || dir == 72)
        Y--; // up
    else if(dir == 'd' || dir == 77)
        X++; // right
    else if(dir == 'i' || dir == 75)
        X--; // left
    else if(dir == 'b' || dir == 80)
        Y++; // down
    draw();
}

void point::movewithtrace(char dir)
{
    dir = getch();
    if(dir=='/')
    {
        X--;
        Y--;
    }
    else if(dir == 'a' || dir == 72)
        Y--; // up
    else if(dir == 'd' || dir == 77)
        X++; // right
    else if(dir == 'i' || dir == 75)
        X--;// left
    else if(dir == 'b' || dir == 80)
        Y++; // down
    draw();
}

What I have in line.cpp so far:

void line::setline(int t, char d, point o)
{
    size = t;
    direction = d;
    origin = o;
}

void line::drawline()
{
    point aux = origin;
    aux.draw();
    for(int c = 1; c < size; c++)
    {
        aux.movewithtrace(direction);
    }
}

void line::eraseline()
{
    line aux = *this;
    aux.origin.SetCharacter(' ');
    aux.drawline();
}

void line::moveline(char dir)
{
    for(int c = 1; c < size; c++)
    {
        eraseline();
        origin.withtrace(dir);
        drawline();
    }
}

What I have in main:

{
    point p1;
    line l1, l2;
    p1.setpoint(8, 6, 3, '@');
    p1.draw();
    char mp = getch();
    l1.setline(6, 'b', p1);
    l1.drawline();
    l1.moverline(mp);
}

Answer 1

The first thing your move and movewithtrace functions do is overwrite the passed-ion dir with the result of getch() . This is probably not what you want. As a result, your drawline function would chew up all your input, assuming getch is a get-character-from-input function.

Your moveline function probably shouldn't have a loop in it; that's covered by eraseline and drawline .

If you need a better answer, you'll need to describe more about the environment you're running in and what all the class members and methods do, as well as the external functions you're calling. I can't even tell if you're drawing pixels or ASCII-art characters.

PS This is why comments in code are helpful: by explaining in English what you're trying to do, both the design and the implementation can be checked. Without documentation, everyone's just guessing, including yourself.