Thread: exercise from Stroustrup's text book

  1. #1
    Registered User
    Join Date
    Feb 2014

    exercise from Stroustrup's text book

    This is from chapter 13. Create a class that draws a box with rounded corners. I got the math figured out, but for some reason the lines are not being drawn to the screen. What could be the problem?

    struct Box:Shape {
      Box(Point xxyy, int ww, int hh);
      void Top_segment();
      void Bottom_segment();
      void Left_side_segment();
      void Right_side_segment();
      void draw_lines() const;
      int height() const {
        return h;
      } int width() const {
        return w;
    } private:
       Point xy;                    //left most corner
      Lines cornerless_box;         // create a box with no corners using line segments
      int h;                        // height
      int w;                        // width
      double width_tenth;           //10% of the width that will calculate the length to remove from each side to make room for the arcs
    Box::Box(Point xxyy, int ww, int hh):w(ww), h(hh), xy(xxyy)
      width_tenth = (xy.x + w) * 0.10;
      if (h <= 0 || w <= 0)
        error("Bad rectangle: non-positive side");
    void Box::Top_segment()
      double top_seg_begin_w;       //where the line segment will begin after deducting 10% of w;
      double top_seg_end_w;         //where the line segment will end after deducting 10% of w;
      top_seg_begin_w = xy.x + width_tenth;
      top_seg_end_w = (xy.x + w) - width_tenth;
      double top_seg_y = xy.y;
      cornerless_box.add(Point(top_seg_begin_w, top_seg_y),
                         Point(top_seg_end_w, top_seg_y));
    void Box::Bottom_segment()
      double bottom_seg_begin_w;
      double bottom_seg_end_w;
      bottom_seg_begin_w = xy.x + width_tenth;
      bottom_seg_end_w = (xy.x + w) - width_tenth;
      double y_bottom = xy.y + h;
      cornerless_box.add(Point(bottom_seg_begin_w, y_bottom),
                         Point(bottom_seg_end_w, y_bottom));
    void Box::Left_side_segment()
      double left_seg_begin_h;
      double left_seg_end_h;
      left_seg_begin_h = xy.y + width_tenth;
      left_seg_end_h = (xy.y + h) - width_tenth;
      double x_left = xy.x;
      cornerless_box.add(Point(x_left, left_seg_begin_h),
                         Point(x_left, left_seg_end_h));
    void Box::Right_side_segment()
      double right_seg_begin_h;
      double right_seg_end_h;
      right_seg_begin_h = xy.y + width_tenth;
      right_seg_end_h = (xy.y + h) - width_tenth;
      double x_right = xy.x + w;
      cornerless_box.add(Point(x_right, right_seg_begin_h),
                         Point(x_right, right_seg_end_h));
    Last edited by Salem; 02-03-2014 at 12:27 AM. Reason: removed pointless font abuse - code formats properly - use past as text!

  2. #2
    Join Date
    Oct 2007
    Inside my computer
    I don't see how the struct is used, nor do I see draw_lines which says to me to draw to screen.
    Also, indent your code when posting.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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