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Template. Numerical Array.

leeto (37)
I what to implement to my Template operator * .
So, Very simple idea.
There is <Template> Array which purpose is container like vector for classes
There is class Point, each object of contain two coordinate x and y.
So,
1. I wanna fill Array with objects from Point class
2. Multiply each objects from this vector to a factor
3. And print all this bunch of objects ()...

Compile error :
1>------ Build started: Project: HP_4.2b_Ex2, Configuration: Release Win32 ------
1> main.cpp
1>main.cpp(21): error C2440: 'initializing' : cannot convert from 'Point' to 'Array<Type>'
1> with
1> [
1> Type=Point
1> ]
1> No constructor could take the source type, or constructor overload resolution was ambiguous
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

code : 
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//array.h
#ifndef Array_H
#define Array_H

template <class Type> //Remove the "=double" default parameter.
class Array
{
protected:
  int m_size;
  Type* m_data; //m_data should be a pointer, since you want to allocate data to it

public:
  Array();
  Array(int new_size);
  Array(const Array<Type>& ar);
  ~Array(); //Don't make your destructor virtual. There is no reason to do it.
  Type& operator * (double factor) const;
  Type& operator [] (int index);
  int Size() const;
  void Swap(Array& ar);  
};



#endif

//************
//************

//point.h

#include "array.h"
#include <sstream>
#include <iostream>
using namespace std;


class Point
{
private:
    double m_x;                                
    double m_y;                                
public:
    // Constructors
    Point(): m_x(0), m_y(0) {};                            
	Point(double new_x, double new_y) : m_x(new_x), m_y(new_y) {};
	friend ostream& operator << (ostream& os, const Point& point)
{
    return os << point.ToString();
}
	std::string Point::ToString(void) const                // create a string representation of a point
{
// create a string like: “Point(1.5, 3.9)”
      std::ostringstream os;
    os << m_x << " , " << m_y;
    std::string double_string = os.str();
 
    return "Point(" + double_string + ")";
}
};

//************
//************
//************
//************

//array.cpp
#include "Array.h"
#include <sstream>
#include <iostream>
#include <exception>
using namespace std;
#ifndef Array_CPP
#define Array_CPP


template <class Type>
Array<Type>::Array() : m_size(10), m_data(0) 
{
}
template <class Type>
Array<Type>::Array(int new_size) : m_size(new_size), m_data(new Type[new_size])
{ 
}

template <class Type>
Array<Type>::~Array()
{
  //Technically, the if is not necessary
  if(m_data)
  {
    delete[] m_data;
    m_data = 0;
  }

  //Not necessary either, but just to be clean
  m_size = 0;
}


template <class Type> 
Type& Array<Type>::operator [] (int index) 
{
    cout << "Array [] operator" << endl;
 
    if (index > this->m_size)
	{
        cout << "i am hreeeee" << endl;
        return this->m_data[0];
	}
    return m_data[index];
}
template<class Type>
int Array<Type>::Size() const
{
	return this->m_size; 
}

template<class Type>
Type& Array<Type>::operator * (double factor) const
{
Array<Type> output(Array<Type>::Size());
for(int i=0; i<Array::Size(); i++)
	{
output[i] = Array<T>::operator[](i) * factor;
	}
return output;
}


#endif //Array_CPP

//************
//************
//************
//************

//main.cpp
		#include "point.h"
		
		#include <iostream>
		#include "array.cpp"
		using namespace std;

int main()
{
			  //Create two Point arrays and test the operators
    Array<Point> pArray1(5);
    Array<Point> pArray2(5);
    //initialize
    for(int i=0; i<pArray1.Size(); i++) pArray1[i] = Point(i, i);
    for(int i=0; i<pArray2.Size(); i++) pArray2[i] = Point(2*i, 2*i);
 
    //Numeric Array's operations not working for Point objects
 
 
    cout << "times PointArray1 by 3 and print out the new array: "<< endl;
    Array<Point> answ1 = pArray1 * 3;
	
    for(int i=0; i<answ1.Size(); i++){
        cout << answ1[i] << endl;

    }
 

	
}
vlad from moscow (6539)
Here

for(int i=0; i<pArray1.Size(); i++) pArray1[i] = Point(i, i);

you are trying to assign object of type Point to an object of type Array<Point>

Sorry I am wrong I thought that this Array<Point> pArray1(5); is the definition of an array.

I see an error in the following definition


template<class Type>
Type& Array<Type>::operator * (double factor) const
{
Array<Type> output(Array<Type>::Size());
for(int i=0; i<Array::Size(); i++)
{
output[i] = Array<T>::operator[](i) * factor;
}
return output;
}

Your template parameter is Type but in the statement

output[i] = Array<T>::operator[](i) * factor;

you use template parameter T
Last edited on
leeto (37)
O my god... so silly mistake... I re - wrote already but compiler again
give me the same error :

1>------ Build started: Project: HP_4.2b_Ex2, Configuration: Release Win32 ------
1> main.cpp
1>main.cpp(23): error C2440: 'initializing' : cannot convert from 'Point' to 'Array<Type>'
1> with
1> [
1> Type=Point
1> ]
1> No constructor could take the source type, or constructor overload resolution was ambiguous
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========


main.cpp(23): Array<Point> answ1 = pArray1 * 3;
under red line: pArray1
and pop -up helper tell that : Error: no suitable user defined conversion from "Point " to Array<Point> exist
vlad from moscow (6539)
Your operator is defined as

Type& operator * (double factor) const;

In case if the Type is the Point then you are trying to assign an object of type Point to an object of type Array<Point>:

Array<Point> answ1 = pArray1 * 3;
leeto (37)
how should I re-write my code ... Please help

last edition: 

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//array.h
#ifndef Array_H
#define Array_H

template <class Type> //Remove the "=double" default parameter.
class Array
{
protected:
  int m_size;
  Type* m_data; //m_data should be a pointer, since you want to allocate data to it

public:
  Array();
  Array(int new_size);
  ~Array(); //Don't make your destructor virtual. There is no reason to do it.
  Array<Type>& operator=(const Array& ar); //Const correctness here.
  Type& operator * (double factor) const;
  Type& operator [] (int index);
  const Type& operator [] (int index) const;
  int Size() const;
};
//****************
//****************
//****************


#endif

//point.h

#include "array.h"
#include <sstream>
#include <iostream>
using namespace std;


class Point
{
private:
    double m_x;                                
    double m_y;                                
public:
    // Constructors
    Point(): m_x(0), m_y(0) {};                            
	Point(double new_x, double new_y) : m_x(new_x), m_y(new_y) {};
	friend ostream& operator << (ostream& os, const Point& point)
{
    return os << point.ToString();
}
	std::string Point::ToString(void) const                // create a string representation of a point
{
// create a string like: “Point(1.5, 3.9)”
      std::ostringstream os;
    os << m_x << " , " << m_y;
    std::string double_string = os.str();
 
    return "Point(" + double_string + ")";

}
	Point Point::operator * (double factor) const;
	Point& Point::operator *= (double factor); 
};

//****************
//****************
//****************

//array.cpp
#include "Array.h"
#include <sstream>
#include <iostream>
#include <exception>
using namespace std;
#ifndef Array_CPP
#define Array_CPP


template <class Type>
Array<Type>::Array() : m_size(10), m_data(0) 
{
}
template <class Type>
Array<Type>::Array(int new_size) : m_size(new_size), m_data(new Type[new_size])
{ 
}

template <class Type>
Array<Type>::~Array()
{
  //Technically, the if is not necessary
  if(m_data)
  {
    delete[] m_data;
    m_data = 0;
  }

  //Not necessary either, but just to be clean
  m_size = 0;
}



template <class Type>
Array<Type>& Array<Type>::operator=(const Array& ar)
{
  //Check self assign:
  if(this == &ar) {return *this;}

  Array<Type> copy(ar); //Create a copy of ar; If this fails, then *this will not be changed, and nothing will leak

  //Succeeded creating copy. Now we can put it inside this
  this->Swap(copy); //And then swap the copy into this!

  return *this;
}





template <class Type> 
Type& Array<Type>::operator [] (int index) 
{
    //cout << "Array [] operator" << endl;
 
    if (index > this->m_size)
	{
        cout << "i am hreeeee" << endl;
        return this->m_data[0];
	}
    return m_data[index];
}

template <class Type> 
 const Type& Array<Type>::operator [] (int index) const
 {
  //  cout << "Array [] operator" << endl;
 
    if (index > this->m_size)
	{
        cout << "i am hreeeee" << endl;
        return this->m_data[0];
	}
    return m_data[index];
}

template<class Type>
int Array<Type>::Size() const
{
	return this->m_size; 
}

template<class Type>
Type& Array<Type>::operator * (double factor) const
{
Array<Type> output(Array<Type>::Size());
for(int i=0; i<Array::Size(); i++)
	{
output[i] = (*this)[i] * factor;
return output;
	}

}

//****************
//****************
//****************

#endif //Array_CPP


#include "array.h"
#include "Point.h"
#include <sstream>
#include <iostream>
using namespace std;

Point Point::operator * (double factor) const
{
    return Point(m_x * factor, m_y * factor);
}


	Point& Point::operator *= (double factor)
	{
    Point tmp = (*this) * factor;
    *this = tmp;
 
    return *this;
	}
//****************
//****************
//****************

//main.cpp
		#include "point.h"
		#include <iostream>
		#include "array.cpp"
		using namespace std;

int main()
{
			  //Create two Point arrays and test the operators
    Array<Point> pArray1(5);
    Array<Point> pArray2(5);
    //initialize
    for(int i=0; i<pArray1.Size(); i++) pArray1[i] = Point(i, i);
    for(int i=0; i<pArray2.Size(); i++) pArray2[i] = Point(2*i, 2*i);

    //Numeric Array's operations not working for Point objects
 
 
    cout << "times PointArray1 by 3 and print out the new array: "<< endl;
    Array<Point> answ1 = pArray1 * 3;
	
    for(int i=0; i<answ1.Size(); i++){
        cout << answ1[i] << endl;

    }
 

	
}


1>------ Build started: Project: HP_4.2b_Ex2, Configuration: Release Win32 ------
1> Array.cpp
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========

1>------ Build started: Project: HP_4.2b_Ex2, Configuration: Release Win32 ------
1> Point.cpp
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========


1>------ Build started: Project: HP_4.2b_Ex2, Configuration: Release Win32 ------
1> main.cpp
1>main.cpp(20): error C2440: 'initializing' : cannot convert from 'Point' to 'Array<Type>'
1> with
1> [
1> Type=Point
1> ]
1> No constructor could take the source type, or constructor overload resolution was ambiguous
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
Last edited on
leeto (37)
I implement your ideas !!! Everything fine !!!
could you check on other silly mistakes please


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template <class Type> //Remove the "=double" default parameter.
class Array
{
protected:
  int m_size;
  Type* m_data; //m_data should be a pointer, since you want to allocate data to it
 
public:
  Array();
  Array(int new_size);
  ~Array(); //Don't make your destructor virtual. There is no reason to do it.
  Array<Type>& operator=(const Array& ar); //Const correctness here.
  //Type& operator * (double factor) const;
  Array operator *(double factor) const;   // я это имел ввиду (про header)
  Type& operator [] (int index);
  const Type& operator [] (int index) const;
  int Size() const;
};
//****************
//****************
//****************
 
#include <sstream>
#include <iostream>
using namespace std;
 
 
class Point
{
private:
    double m_x;                                
    double m_y;                                
public:
    // Constructors
    Point(): m_x(0), m_y(0) {};                            
    Point(double new_x, double new_y) : m_x(new_x), m_y(new_y) {};
    friend ostream& operator << (ostream& os, const Point& point)
{
    return os << point.ToString();
}
    //std::string Point::ToString(void) const                // create a string representation of a point
   string ToString() const
{
// create a string like: “Point(1.5, 3.9)”
      std::ostringstream os;
    os << m_x << " , " << m_y;
    std::string double_string = os.str();
 
    return "Point(" + double_string + ")";
 
}
    //Point Point::operator * (double factor) const;
    Point operator *(double factor) const;   // итак в классе, Point:: не нужно
    //Point& Point::operator *= (double factor); 
    Point & operator *=(double factor);
};
 
//****************
//****************
//****************
 
//array.cpp
//#include "Array.h"
//#include <sstream>
//#include <iostream>
#include <exception>
//using namespace std;
//#ifndef Array_CPP
//#define Array_CPP
 
 
template <class Type>
Array<Type>::Array() : m_size(10), m_data(0) // странно получается, размер 10, а данных нет
{
}
template <class Type>
Array<Type>::Array(int new_size) : m_size(new_size), m_data(new Type[new_size])
{ 
}
 
template <class Type>
Array<Type>::~Array()
{
  //Technically, the if is not necessary
  if(m_data)
  {
    delete[] m_data;
    m_data = 0;
  }
 
  //Not necessary either, but just to be clean
  m_size = 0;
}
 
 
 
template <class Type>
Array<Type>& Array<Type>::operator=(const Array& ar)
{
  //Check self assign:
  if(this == &ar) {return *this;}
 
  Array<Type> copy(ar); //Create a copy of ar; If this fails, then *this will not be changed, and nothing will leak
 
  //Succeeded creating copy. Now we can put it inside this
  this->Swap(copy); //And then swap the copy into this!
 
  return *this;
}
 
 
 
 
 
template <class Type> 
Type& Array<Type>::operator [] (int index) 
{
    //cout << "Array [] operator" << endl;
 
    if (index > this->m_size)
    {
        cout << "i am hreeeee" << endl;
        return this->m_data[0];
    }
    return m_data[index];
}
 
template <class Type> 
 const Type& Array<Type>::operator [] (int index) const
 {
  //  cout << "Array [] operator" << endl;
 
    if (index > this->m_size)
    {
        cout << "i am hreeeee" << endl;
        return this->m_data[0];
    }
    return m_data[index];
}
 
template<class Type>
int Array<Type>::Size() const
{
    return this->m_size; 
}
 
template<class Type>
//Type& Array<Type>::operator * (double factor) const
Array<Type> Array<Type>::operator *(double factor) const
{
   Array<Type> output(Array<Type>::Size());
   for(int i=0; i<Array::Size(); i++)
   {
      output[i] = (*this)[i] * factor;
      //return output;
   }
   return output;
}
 
//****************
//****************
//****************
 
//#endif //Array_CPP
 
 
//#include "array.h"
//#include "Point.h"
//#include <sstream>
//#include <iostream>
//using namespace std;
 
Point Point::operator * (double factor) const
{
    return Point(m_x * factor, m_y * factor);
}
 
 
    Point& Point::operator *= (double factor)
    {
    Point tmp = (*this) * factor;
    *this = tmp;
 
    return *this;
    }
//****************
//****************
//****************
 
//main.cpp
//        #include "point.h"
//        #include <iostream>
//        #include "array.cpp"
//        using namespace std;
 
int main()
{
              //Create two Point arrays and test the operators
    Array<Point> pArray1(5);
    Array<Point> pArray2(5);
    //initialize
    for(int i=0; i<pArray1.Size(); i++) pArray1[i] = Point(i, i);
    for(int i=0; i<pArray2.Size(); i++) pArray2[i] = Point(2*i, 2*i);
 
    //Numeric Array's operations not working for Point objects
 
 
    cout << "times PointArray1 by 3 and print out the new array: "<< endl;
    Array<Point> answ1 = pArray1 * 3;
    
    for(int i=0; i<answ1.Size(); i++){
        cout << answ1[i] << endl;
 
    }
 
 
    
}
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