Cant display lines!!!

[MissKaramatic]

Hi! I'm trying to write a code that displays lines between user designated points with circles at each point, but I can't get the lines to display! I'm at a loss on what to do and need fresh eyes on the subject.

#include <iostream>
#include "graph1.h"

using namespace std;

//Function Prototypes Follow
void getNoPoints(int* no_points);
void getPoints(int* x, int* y,int no_points);
void drawPolyLine(int* x, int* y, int no_points,int objects[]);

int main()
{
  //Variable Declaration/Initialization

  int no_points = 0;
  const int MAX_POINTS = 10;
  int x[MAX_POINTS];
  int y[MAX_POINTS];
  int no_circles = 0;
  int objects[MAX_POINTS];
  
  //Display Graphics Window
  displayGraphics();

  //Get the number of points (pass the address of no_points )
  getNoPoints(&no_points);

  //Get the data for the points
  getPoints(x,y,no_points);

  //Draw the polyline
  drawPolyLine(x,y,no_points,objects);

  return 0;
}

//Function Implementation Follows
void getNoPoints(int* no_points)
{
	cout<<"Enter # of points: ";
	cin>>*no_points;
}
void getPoints(int* x, int* y,int no_points)
{
	//Variable Declaration/Initiliation
	int i=0;

	for(i=0;i<no_points;i++)
	{
	cout<<"Enter x/y coord for point #"<<(i+1)<<": ";
	cin>>x[i]>>y[i];
	}
}

void drawPolyLine(int* x, int* y, int no_points,int objects[])
{
	int i=0;
	
	for (i = 0; i < no_points;)
	{
	objects[i] = drawLine(x[i],y[i],x[++i],y[++i],1);
    setColor(objects[i],255,255,0);
	}

  //Display each circle

  for (i = 0; i < no_points; i++)
  {
    objects[i] = drawCircle(5,x[i],y[i]);
	setColor(objects[i],255,0,0);
  }
}

I imagine the error is in this segment:

int i=0;
	
	for (i = 0; i < no_points;)
	{
	objects[i] = drawLine(x[i],y[i],x[++i],y[++i],1);
    setColor(objects[i],255,255,0);
	}

[TheIdeasMan]

Hi,

First up, please use code tags. Edit your post, select all the code, then press the <> button on the format menu.

Also some indentation would be good.

for (i = 0; i < no_points;)
{
objects[i] = drawLine(x[i],y[i],x[++i],y[++i],1);

That looks like undefined behaviour to me, because of the multiple ++i in one statement.

Use another variable which is the next point, and provide that as an argument.

[MissKaramatic]

Sorry for all the issues, I'm new here. But as for the code, I'm not sure I understand what you mean by using another variable as the next point?

[TheIdeasMan]

Hi,

Well, you have a drawLine function which takes x and y coordinates. Assign the values you want to variables NextX, NextY say, then call your function with those variables:

objects[i] = drawLine(ThisX, ThisY, NextX, NextY,1);

Please update your post so it uses code tags.

[MissKaramatic]

I have the variable I as a user input coordinate so that when the program asks for coordinates for point 1,point 2,etc., it starts at point one, then the i++ goes on to the next point(2) and so on(like with the draw circles function). I can't just assign the variables values because it's user defined values,unless I'm not understanding what you mean?Also,if I set next x and next y to 0 then how would I code the program to have it go on to different variables until it came to 6,and the user doesn't even have to use six?I'm very confused.

[TheIdeasMan]

Ok,

so what does you code look like now?

Do you understand how I meant that:

ThisX = x[i];

and

int m = i+1; // avoid incrementing i
NextX = x[m];

Btw, I would prefer not to use i or j as variable names, they can cause problems because they are hard to see when there are lots of them in code.

Use a normal for loop:

for (Z = 0; Z < no_points;++Z)

:+)