Adding 2 polygons together

[Hypnotik]

Hey everyone. I'm writing a program which allows the user to enter information about 2 shapes, either a square, triangle, or rectangle, then 'adds' the shaps together. The resulting shape is a polygon. I understand how this is done, just not sure about the code. I need to overload the + operator to add the shapes. Also I know that I need to make a comparison between sides begin combined, and subtract the smaller side from the area. Also I understand that I need to renumber the sides. I'm just not sure how to do this. Code is posted below

 
#include <iostream>
using namespace std;
class Polygon
{
  protected:
    int length[20],num_sides;
  public:
    void set_values (int sl[], int n);
    Polygon();
    ~Polygon(){}
    void dimensions(int length[],int a);
    void perimeter(int length[],int a);
    void area (int length[],int a);
    Polygon operator+(Polygon &);
};
Polygon::Polygon()
{
    int i;
    for (i=0;i<20;++i)
    {
        length[i]=0;
    }
    num_sides=0;
}
void Polygon::set_values(int sl[],int n)
{
    int i=0,j=1, length[20];
    for(i=0;i<n;++i)
    {
        length[i]=sl[i];
    }
    perimeter(length,n);
    area(length,n);
    dimensions(length,n);
}
//Polygon Polygon::operator+(Polygon &value)
//{
//        return(0);
//}
void Polygon::dimensions(int length[], int a)
{
    int i;
    if (a==1)
    {
        cout<<"Dimensions:  "<<length[0]<<"x"<<length[0]<<endl;
    }
    else if (a==2)
    {
        cout<<"Dimensions:  "<<length[0]<<"x"<<length[1]<<endl;
    }
    else
        cout<<"Dimensions:  "<<length[0]<<"x"<<length[1]<<"x"<<length[2]<<endl;
}
void Polygon::perimeter(int length[],int a)
{
    int perim=0,i=0;
    if (a==2)
    {
        perim=(2*length[0]+2*length[1]);    
    }
    else if (a==1)
    {
        perim=4*length[0];
    }
    else if (a==3)
    {
        perim=length[0]+length[1]+length[2];
    }
    cout<<"Perimeter:   "<<perim<<endl;
}
void Polygon::area(int length[],int a)
{
    int area=0;
    if (a==1)
    {
        area=length[0]*length[0];
    }
    else if (a==2)
    {
        area=length[0]*length[1];    
    }
    else if (a==3)
    {
        area=(length[0]*length[1])/2;
    }
    cout<<"Area:        "<<area<<endl;
}
class Rectangle: public Polygon 
{
public:
    Rectangle(){}
    ~Rectangle(){}
    void set_values();
};
void Rectangle::set_values()
{
    int i, rs[4]={0};
    cout<<"Enter the length of your side: "<<endl;
    cin>>rs[0];
    rs[2]=rs[0];
    cout<<"Enter the width of your side: "<<endl;
    cin>>rs[1];
    rs[3]=rs[1];
    Polygon::set_values(rs,2);
}
class Triangle: public Polygon
{
public:
    Triangle(){}
    ~Triangle(){}
    void set_values ();
};
void Triangle::set_values()
{
    int ls[3]={0};
    cout<<"Enter the length of side 1 of your triangle: "<<endl;
    cin>>ls[0];
    cout<<"Enter the length of side 2 of your triangle: "<<endl;
    cin>>ls[1];
    cout<<"Enter the length of side 3 of your triangle: "<<endl;
    cin>>ls[2];
    Polygon::set_values(ls, 3);
}
class Square: public Polygon
{
public:
    Square (){}
    ~Square(){}
    void set_values ();
};
void Square::set_values()
{
    int i=0, ss[1]={0};
    cout<<"Enter the length of the side of your square: "<<endl;
    cin>>ss[0];
    Polygon::set_values(ss,1);
}
void main () 
{
  int ans=0,sel=0,sel1=0,n=0;
  Polygon x,y,z;
  Rectangle rect;
  Triangle trgl;
  Square sqr;
  cout<<"What would you like to do?"<<endl;
  do
  {
  cout<<"Enter 1 to enter and display dimensions of a shape."<<endl;
  cout<<"Enter 2 to add two shapes."<<endl;
  cin>>sel;
  if (sel==1)
  {
    do
      {
      cout<<"Enter 1 for rectangle, 2 for square, 3 for triangle"<<endl;
      cin>>ans;
      if(ans==1)
      {
          cout<<"You have chosen a rectangle!"<<endl;
          rect.set_values();
      }
      else if (ans==2)
      {
          cout<<"You have chosen a square!"<<endl;
          sqr.set_values();
      }
      else if (ans==3)
      {
          cout<<"You have chosen a triangle!"<<endl;
          trgl.set_values();
      }
      else
          cout<<"Make a selection from the menu!"<<endl<<endl;
      }
      while (ans<1||ans>3);
  }
  else if (sel==2)
  {
      while (n<2)
      {
      cout<<"Select your shape: "<<endl;
      cout<<"Enter 1 for rectangle, 2 for square, 3 for triangle."<<endl;
      cin>>sel1;
      if (sel==1)
      {
          cout<<"Enter your dimensions for the rectangle"<<endl;
          rect.set_values();
          ++n;
      }
      else if (sel==2)
      {
          cout<<"Enter your dimensions for the square"<<endl;
          sqr.set_values();
          ++n;
      }
      else if (sel==3)
      {
          cout<<"Enter your dimensions for the triangle"<<endl;
          trgl.set_values();
          ++n;
      }
      else
          cout<<"Make a selection from the menu."<<endl;
      }
  }
  else
      cout<<"Make a selection from the menu."<<endl;
  }
  while(sel<1||sel>2);
}
 
 

Thanks for looking,
J

[ravenspoint]

Also I know that I need to make a comparison between sides begin combined, and subtract the smaller side from the area.

I do not understand what this means.

[Hypnotik]

I do not understand what this means.

Heh...yeah that doesn't make sense. Say I am adding a triangle and a rectangle. When those shapes are added together, I will have a shape which is now neither a triangle or rectangle...it will be a polygon. The length of the side that is on the triangle, where the rectangle is added, will change. That is where the comparison comes in. The length of the side (on the triangle) will have to have the length of the rectangle side subtracted from it.

Say you have a triangle with each side being 3 inches, and you have a rectangle with a side that is 2 inches. When you combine the two sides, you have to subtract the 2 inches off, because you now have some odd shape, but 1 inch is left on the original triangle side.

Ugh...does that make sense, it's hard to explain without a diagram.

J

[ravenspoint]

How do you decide which side to make common between the two polygons?

[ravenspoint]

Of, course, if you use only squares and triangles with equal sides, it doesn't matter.

[Hypnotik]

How do you decide which side to make common between the two polygons?

I can pick any side....the instructor said it doesn't matter

J

[ravenspoint]

It doesn't matter?!?

This seems to be a poorly defined problem. No wonder you are having difficulties with it.

In order to design an algorithm to do something, the designer needs to know what is required.

I suggest you come up with what are sometimes called "use cases". Invent some concrete examples of "adding" polygons together and write down the inputs and outputs. This exercise should show what your options are, and you can pin down exactly what you want to do.

Some questions you might want to think about.

Do you want to keep the area of the summed polygons equal to the summed area of the originals?

How about the perimiter?

If I remember the original code, then it can only handle squares, rectangles and triangles. How many vertices does the sum of a triangle and a square have? How will you code deal with more than 4?

[Hypnotik]

Ok so I've worked on the problem some more, and unfortunately I can't edit the other post to remove that code. I have added 6 overloaded operator functions however I am receiving an error. The error has to do with the return value in those newly added functions. I receive a syntax error ';' on the return statement line, however if I remove the semicolon I receive another error.

 
#include <iostream>
using namespace std;
class Polygon
{
  protected:
    int length[20],num_sides;
  public:
    void set_values (int sl[], int n);
    Polygon();
    ~Polygon(){}
    void dimensions(int length[],int a);
    void perimeter(int length[],int a);
    void area (int length[],int a);
 
};
Polygon::Polygon()
{
    int i;
    for (i=0;i<20;++i)
    {
        length[i]=0;
    }
    num_sides=0;
}
void Polygon::set_values(int sl[],int n)
{
    int i=0,j=1, length[20];
    for(i=0;i<n;++i)
    {
        length[i]=sl[i];
    }
    perimeter(length,n);
    area(length,n);
    dimensions(length,n);
}
 
void Polygon::dimensions(int length[], int a)
{
    int i;
    if (a==1)
    {
        cout<<"Dimensions:  "<<length[0]<<"x"<<length[0]<<endl;
    }
    else if (a==2)
    {
        cout<<"Dimensions:  "<<length[0]<<"x"<<length[1]<<endl;
    }
    else
        cout<<"Dimensions:  "<<length[0]<<"x"<<length[1]<<"x"<<length[2]<<endl;
}
void Polygon::perimeter(int length[],int a)
{
    int perim=0,i=0;
    if (a==2)
    {
        perim=(2*length[0]+2*length[1]);    
    }
    else if (a==1)
    {
        perim=4*length[0];
    }
    else if (a==3)
    {
        perim=length[0]+length[1]+length[2];
    }
    cout<<"Perimeter:   "<<perim<<endl;
}
void Polygon::area(int length[],int a)
{
    int area=0;
    if (a==1)
    {
        area=length[0]*length[0];
    }
    else if (a==2)
    {
        area=length[0]*length[1];    
    }
    else if (a==3)
    {
        area=(length[0]*length[1])/2;
    }
    cout<<"Area:        "<<area<<endl;
}
class Rectangle: public Polygon 
{
public:
    Rectangle(){}
    ~Rectangle(){}
    Polygon Rectangle::operator+(Rectangle A);
    void set_values();
};
void Rectangle::set_values()
{
    int i, rs[4]={0};
    cout<<"Enter the length of your side: "<<endl;
    cin>>rs[0];
    rs[2]=rs[0];
    cout<<"Enter the width of your side: "<<endl;
    cin>>rs[1];
    rs[3]=rs[1];
    Polygon::set_values(rs,2);
}
Polygon Rectangle::operator +(Rectangle A)
{
    Polygon temp;
    return (Polygon);
}
class Triangle: public Polygon
{
public:
    Triangle(){}
    ~Triangle(){}
    Polygon Triangle::operator+(Triangle A);
    Polygon Triangle::operator +(Rectangle A);
    void set_values ();
};
void Triangle::set_values()
{
    int ls[3]={0};
    cout<<"Enter the length of side 1 of your triangle: "<<endl;
    cin>>ls[0];
    cout<<"Enter the length of side 2 of your triangle: "<<endl;
    cin>>ls[1];
    cout<<"Enter the length of side 3 of your triangle: "<<endl;
    cin>>ls[2];
    Polygon::set_values(ls, 3);
}
Polygon Triangle::operator+(Triangle A)
{
    Polygon temp;
    return(temp);
}
Polygon Triangle::operator +(Rectangle A)
{
    Polygon temp;
    return(Polygon);
}
class Square: public Polygon
{
public:
    Square (){}
    ~Square(){}
    Polygon Square::operator+(Square A);
    Polygon Square::operator +(Rectangle A);
    Polygon Square::operator +(Triangle A);
    void set_values ();
};
void Square::set_values()
{
    int i=0, ss[1]={0};
    cout<<"Enter the length of the side of your square: "<<endl;
    cin>>ss[0];
    Polygon::set_values(ss,1);
}
Polygon Square::operator +(Square A)
{
    Polygon temp;
    return (temp);
}
Polygon Square::operator +(Rectangle A)
{
    Polygon temp;
    if(*this->side1>A.side1)
    {
        *this->side1=*this->side1-A.side1;
        temp.side1=*this->side1;
    }
    return (temp);
}
Polygon Square::operator +(Triangle A)
{
    return (Polygon);
}
void main () 
{
  int ans=0,sel=0,sel1=0,sel2=0,n=0;
  Polygon x,y,z;
  Rectangle rect;
  Triangle trgl;
  Square sqr;
  cout<<"What would you like to do?"<<endl;
  do
  {
  cout<<"Enter 1 to enter and display dimensions of a shape."<<endl;
  cout<<"Enter 2 to add two shapes."<<endl;
  cin>>sel;
  if (sel==1)
  {
    do
      {
      cout<<"Enter 1 for rectangle, 2 for square, 3 for triangle"<<endl;
      cin>>ans;
      if(ans==1)
      {
          cout<<"You have chosen a rectangle!"<<endl;
          rect.set_values();
      }
      else if (ans==2)
      {
          cout<<"You have chosen a square!"<<endl;
          sqr.set_values();
      }
      else if (ans==3)
      {
          cout<<"You have chosen a triangle!"<<endl;
          trgl.set_values();
      }
      else
          cout<<"Make a selection from the menu!"<<endl<<endl;
      }
      while (ans<1||ans>3);
  }
  else if (sel==2)
  {
      cout<<"Select your shape: "<<endl;
      cout<<"Enter 1 for rectangle, 2 for square, 3 for triangle."<<endl;
      cin>>sel1;
      if (sel1==1)
      {
          cout<<"Enter your dimensions for the rectangle"<<endl;
          rect.set_values();
          ++n;
      }
      else if (sel1==2)
      {
          cout<<"Enter your dimensions for the square"<<endl;
          sqr.set_values();
          ++n;
      }
      else if (sel1==3)
      {
          cout<<"Enter your dimensions for the triangle"<<endl;
          trgl.set_values();
          ++n;
      }
      else
      {
          cout<<"Make a selection from the menu."<<endl;
      }
      cout<<"Select your second shape."<<endl;
      cin>>sel2;
      if (sel2==1)
      {
          cout<<"Enter your dimensions for the rectangle"<<endl;
          rect.set_values();
          ++n;
      }
      else if (sel2==2)
      {
          cout<<"Enter your dimensions for the square"<<endl;
          sqr.set_values();
          ++n;
      }
      else if (sel2==3)
      {
          cout<<"Enter your dimensions for the triangle"<<endl;
          trgl.set_values();
          ++n;
      }
      else
      cout<<"Make a selection from the menu."<<endl;
  }
  while(sel<1||sel>2);
  if (sel1==1&&sel2==1)
  {
     x=trgl+trgl;
  }
  else if (sel1==1&&sel2==2||sel1==2&&sel2==1)
  {
     x=sqr+rect;
  }
  else if (sel1==1&&sel2==3||sel1==3&&sel2==1)
  {
      x=trgl+rect;
  }
  else if (sel1==2&&sel2==3||sel1==3&&sel2==2)
  {
      x=sqr+trgl;
  }
  else if (sel1==2&&sel2==2)
  {
      x=sqr+sqr;
  }
  else if (sel1==1&&sel2==1)
  {
      x=rect+rect;
  }
  }
}
 
 

Thanks for looking,

J

[Matthew Page]

Just a stab, but it looks like in some cases you are returning the data type and not a variable of the data type...