Thread: C++ problem with Shape hierarchy ~

Originally Posted by laserlight

You are contradicting yourself. In the first sentence, you say that the source file should not contain the implementation of getShape(), then in the second second you say that the source file should contain the implementation of getShape().


Good. What about getShape.cpp? If it compiles, show your current Main.cpp. If not, show your current getShape.cpp.

I'm not talking about the getShape.cpp, i'm talking about shape and other derived classes, they shouldn't include getShape.cpp. ON the other hand, getShape.cpp is supposed to include circle.h, rectangle.h and square.h. and Main.cpp is only supposed to include shape.h.

Code:

#include <string>
using std::string;
#include <sstream>
#include <iostream>
using namespace std;
#include <iomanip>

#include "circle.h"
#include "square.h"
#include "rectangle.h"



using std::string;
using namespace std;

shape* getShape()
{

do {

string color;
double length, width, rad, side;
string shapetype;
shape *myshape;



cout << "Enter the shape's color (or 'done')..." << endl;
cin >> color;
cout << "Enter shape type..." << endl;
cin >> shapetype;
if (shapetype == "done")
{
return NULL;
}
if (shapetype == "circle")
{
cout << "Enter the radius..." << endl;
cin >> rad;
myshape = new circle(color, rad);
return myshape;
}


if (shapetype == "square")
{
cout << "Enter the side length..." << endl;
cin >> side;
myshape = new square(color, side);
return myshape;
}

if (shapetype == "rectangle")
{
cout << "Enter the length..." << endl;
cin >> length;
cout << "Enter the width..." << endl;
cin >> width;
myshape = new rectangle(color, width, length);
return myshape;
}
else{
cout << "Invalid input" << endl;
continue;
}


}while (true);

}

Originally Posted by laserlight

Yes, but I was talking about getShape.cpp, so there was a miscommunication

Anyway, I gather that you posted getShape.cpp. What are the errors that you get when you compile it?

nothing, its just that main.cpp doesn't recognize getShape(). It doesn't recognize, circle, square or rectangle either.

Code:

int main()

{
      shape* dshape[10];
      for ( int i = 0; i < 10; ++i)
      dshape[i]->getShape();
      dshape[i]->toString();
}

I tried to call getShape() other ways but it doesnt recognize it either.

Originally Posted by laserlight

Right, then you should have posted your main.cpp instead.


One idea here is that your global main function does not need to know about circle, square, or rectangle. The code that handles the creation of the correct object is in getShape(). All that the global main function needs to know is the shape interface, and that is provided by including shape.h.

However, to call getShape(), the global main function needs to know something about it, and that can be provided by declaring it:

Code:

#include "shape.h"

shape* getShape();

int main()
{
    shape* shape_obj = getShape();
    shape_obj->toString();
}

Can i sort toString by area like this?

Code:

for (i=0; i<10-1; i++)
for (j=i+1; j< 10; j++)

if (dshape[i]->area()>dshape[j])
{
 temp=dshape[i];
 dshape[i]=dshape[j];
 dshape[j]=temp;
 }
dshape[i]->toString();

Originally Posted by laserlight

Your getShape() function only returns a pointer to one shape, so there is nothing to "sort".

I did this but it craches

Code:

	shape* mshape[10];
	int i;
	
	for ( i = 0; i < 2; ++i){
    shape *shape_obj = getShape();
	mshape[10] = shape_obj ;}

Originally Posted by laserlight

mshape[10] does not exist, since mshape is an array of 10 shape pointers.

How do you suppose i can store the shape* in an array and pring them all at one time with toString()

here is what i did.

Code:

	shape* mshape[10];
	int i, number;
	cout << "CREATING SHAPE(circle, rectangle or square)\n\n" <<endl;
	cout << "\nHow many shape you wish to create?  " << endl;
	
	for ( i = 0; i < number; ++i){
    shape *shape_obj = getShape();
	mshape[i] = shape_obj;} //store shapes into array
	
	for (i = 0; i < number; ++i){
		cout << mshape[i]->toString() << endl;} //print description of shapes

Now i need to sort it

how come i can't sort the mshape[i]->toString() in ascending order depending on the area?

Code:

	 for (int nStartIndex = 0; nStartIndex < number; nStartIndex++)  
 {     
     int nSmallestIndex = nStartIndex;  
   
      
     for (int nCurrentIndex = nStartIndex + 1; nCurrentIndex < number; nCurrentIndex++)  
     {  
            
         if ( mshape[nCurrentIndex]->area() < mshape[nSmallestIndex]->area() )  
              
             nSmallestIndex = nCurrentIndex;  
     }  
   
       
     swap(mshape[nStartIndex]->area(), mshape[nSmallestIndex]->area()); 

 cout << mshape[nStartIndex]->toString << endl;

}

that is what i wrote but it doesn't work.