June 19th, 2012 10:36 AM
#1
generic inheritance
Very simple idea:
Code:
//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;
Array operator *(double factor) const; //
Type& operator [] (int index);
const Type& operator [] (int index) const;
int Size() const;
};
#ifndef Array_cpp
#include "array.cpp"
#endif
#endif //Array_CPP
//*******************
//*******************
//*******************
//*******************
//NumericArray.h
#ifndef NumericArray_H
#define NumericArray_H
template <class Type> //Remove the "=double" default parameter.
class NumericArray: public Array<Type>
{
public:
NumericArray();
NumericArray(int new_size);
~NumericArray(); //Don't make your destructor virtual. There is no reason to do it.
//NumericArray<Type>& operator=(const Array& ar); //Const correctness here.
NumericArray operator *(double factor) 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
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;
//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
//*******************
//*******************
//*******************
//*******************
//NumericArray.cpp
#include "NumericArray.h"
#include <sstream>
#include <iostream>
#include <exception>
using namespace std;
#ifndef NumericArray_CPP
#define NumericArray_CPP
template <class Type>
NumericArray<Type>::NumericArray() : m_size(10), m_data(0) // странно получается, размер 10, а данных нет
{
}
template <class Type>
NumericArray<Type>::NumericArray(int new_size) : m_size(new_size), m_data(new Type[new_size])
{
}
template <class Type>
NumericArray<Type>::~NumericArray()
{
//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>
NumericArray<Type> NumericArray<Type>::operator *(double factor) const
{
NumericArray<Type> output(NumericArray<Type>::Size());
for(int i=0; i<Array::Size(); i++)
{
output[i] = (*this)[i] * factor;
//return output;
}
return output;
}
#endif //NumericArray_CPP
//*******************
//*******************
//*******************
//*******************
#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"
#include <exception>
#include "NumericArray.h"
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;
}
}
//*******************
//*******************
//*******************
//*******************
Many many thanks in advance !
June 19th, 2012 10:57 AM
#2
Re: generic inheritance
Originally Posted by
oteel
Very simple idea:
Where is line 7 and line 15?
June 19th, 2012 11:30 AM
#3
Re: generic inheritance
You don't need to do that. Templates classes only compile the methods that are called. Methods that aren't called aren't compiled. They aren't even checked for legality (apart from proper grammar)
Code:
#include <iostream>
template <typename T>
struct Holder
{
void shift(size_t s)
{m_value <<= s;}
T m_value;
};
int main()
{
Holder<int> ih = {5};
Holder<double> id = {5.5};
ih.shift(1);
//id.shift(1); //Try to uncomment this
std::cout << ih.m_value << " " << id.m_value;
}
Here, we have a "Holder", with a "shift" method. ints can be shifted, but doubles can't. This code compiles, but if you try to insert the call id.shift, then (and only then) will it not compile.
Is your question related to IO?this C++ FAQ LITE article at parashift by Marshall Cline. In particular points 1-6.
June 19th, 2012 11:51 AM
#4
Re: generic inheritance
Originally Posted by
oteel
1>------ Build started: Project: HP3_4.2b_ex2_with_inheritance, Configuration: Release Win32 ------
1> NumericArray.cpp
1>c:\all my\с++\ha level 6\solution\level 6\hp3_4.2b_ex2_with_inheritance\NumericArray.h(7): error C2143: syntax error : missing ',' before '<'
1> c:\all my\с++\ha level 6\solution\level 6\hp3_4.2b_ex2_with_inheritance\NumericArray.h(15) : see reference to class template instantiation 'NumericArray<Type>' being compiled
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
h(7) and h(15) correspond open and close bracket of class
my code :
Code:
//NumericArray.h
#ifndef NumericArray_H
#define NumericArray_H
template <class Type> //Remove the "=double" default parameter.
class NumericArray: public Array<Type>
{
public:
NumericArray();
NumericArray(int new_size);
~NumericArray(); //Don't make your destructor virtual. There is no reason to do it.
//NumericArray<Type>& operator=(const Array& ar); //Const correctness here.
NumericArray operator *(double factor) const; //
};
No, line 7 is this one:
Code:
class NumericArray: public Array<Type>
and it looks like you simply are not including array.h in NumericArray.cpp
Vlad - MS MVP [2007 - 2012] -
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June 19th, 2012 01:50 PM
#5
Re: generic inheritance
Originally Posted by
VladimirF
No, line 7 is this one:
Code:
class NumericArray: public Array<Type>
and it looks like you simply are not including array.h in NumericArray.cpp
So silly mistake... and I also didn't include array.h in NumericArray.h
Last edited by oteel; June 19th, 2012 at 01:54 PM .
June 19th, 2012 01:59 PM
#6
Re: generic inheritance
Originally Posted by
oteel
1>main.obj : error LNK2001: unresolved external symbol "public: class Array<class Point> __thiscall Array<class Point>::operator*(double)const " (??D?$Array@VPoint@@@@QBE?AV0@N@Z)
First, do you know what that error means?
Last edited by Paul McKenzie; June 19th, 2012 at 02:03 PM .
June 19th, 2012 02:01 PM
#7
Re: generic inheritance
Originally Posted by
Paul McKenzie
Where is line 7 and line 15?
now compiler say me if I press ctrl + F7 (MS VS 2010) :
Last edited by oteel; June 19th, 2012 at 02:04 PM .
June 19th, 2012 02:04 PM
#8
Re: generic inheritance
Originally Posted by
Paul McKenzie
First, do you know what that error means?
just a second I post a code last edition
June 19th, 2012 02:08 PM
#9
Re: generic inheritance
Why did you separate NumericArray.h and NumericArray.cpp into different files? NumericArray is a template class -- all the code goes in one file, and then you #include that file.any template class you write goes in one file. I think that naming your template implementation files with a .cpp extension is confusing you.
June 19th, 2012 02:08 PM
#10
Re: generic inheritance
Originally Posted by
oteel
just a second I post a code last edition
Code:
//array.h //array.h //array.h //array.h //array.h //array.h //array.h //array.h //array.h //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);
virtual ~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; //
Type& operator [] (int index);
const Type& operator [] (int index) const;
int Size() const;
};
#ifndef Array_cpp
#include "array.cpp"
#endif
#endif //Array_CPP
//*******************
//*******************
//*******************
//*******************
//NumericArray.h //NumericArray.h //NumericArray.h //NumericArray.h //NumericArray.h //NumericArray.h //NumericArray.h //NumericArray.h //NumericArray.h
#include "array.h"
#ifndef NumericArray_H
#define NumericArray_H
template <class Type> //Remove the "=double" default parameter.
class NumericArray: public Array<Type>
{
public:
NumericArray();
NumericArray(int new_size);
~NumericArray(); //Don't make your destructor virtual. There is no reason to do it.
//NumericArray<Type>& operator=(const Array& ar); //Const correctness here.
NumericArray operator *(double factor) const; //
};
#endif
//*******************
//*******************
//*******************
//*******************
//point.h //point.h //point.h //point.h //point.h //point.h //point.h //point.h //point.h //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
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;
//Point& Point::operator *= (double factor);
Point & operator *=(double factor);
};
//*******************
//*******************
//*******************
//*******************
//array.cpp //array.cpp //array.cpp //array.cpp //array.cpp //array.cpp //array.cpp //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
//*******************
//*******************
//*******************
//*******************
//NumericArray.cpp //NumericArray.cpp //NumericArray.cpp
#include "NumericArray.h"
#include <sstream>
#include <iostream>
#include <exception>
#include "array.h"
using namespace std;
#ifndef NumericArray_CPP
#define NumericArray_CPP
template <class Type>
NumericArray<Type>::NumericArray() : m_size(10), m_data(0) // default filling of array is zeros!
{
}
template <class Type>
NumericArray<Type>::NumericArray(int new_size) : m_size(new_size), m_data(new Type[new_size])
{
}
template <class Type>
NumericArray<Type>::~NumericArray()
{
//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>
NumericArray<Type> NumericArray<Type>::operator *(double factor) const
{
NumericArray<Type> output(NumericArray<Type>::Size());
for(int i=0; i<Array::Size(); i++)
{
output[i] = (*this)[i] * factor;
//return output;
}
return output;
}
#endif //NumericArray_CPP
//*******************
//*******************
//*******************
//*******************
// Point.cpp // Point.cpp // Point.cpp // Point.cpp // Point.cpp // Point.cpp // Point.cpp // Point.cpp
#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 //main.cpp //main.cpp //main.cpp //main.cpp //main.cpp //main.cpp //main.cpp
#include "point.h"
#include <iostream>
#include "array.cpp"
#include <exception>
#include "NumericArray.h"
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;
}
}
//*******************
//*******************
//*******************
//*******************
June 19th, 2012 02:12 PM
#11
Re: generic inheritance
Code:
#include "array.h"
#ifndef NumericArray_H
#define NumericArray_H
Why is array.h outside of the include guards?
Code:
#ifndef NumericArray_H
#define NumericArray_H
#include "array.h"
Second, you're supposed to include the implementation inside of NumericArray.h. All you have is the class definition, so where is the implementation?
June 19th, 2012 02:12 PM
#12
Re: generic inheritance
Originally Posted by
Paul McKenzie
Why did you separate NumericArray.h and NumericArray.cpp into different files? NumericArray is a template class -- all the code goes in one file, and then you #include that file.any template class you write goes in one file. I think that naming your template implementation files with a .cpp extension is confusing you.
I doing what other doing I mean classmates))) If serious, I thinks main purpose of separating is that show new combination of pre processors... like including array.cpp in main not array.h like in class exercises
June 19th, 2012 02:14 PM
#13
Re: generic inheritance
Originally Posted by
Paul McKenzie
Code:
#include "array.h"
#ifndef NumericArray_H
#define NumericArray_H
Why is array.h outside of the include guards?
Code:
#ifndef NumericArray_H
#define NumericArray_H
#include "array.h"
Second, you're supposed to include the implementation inside of NumericArray.h. All you have is the class definition, so where is the implementation?
Regards,
Paul McKenzie
Code:
template<class Type>
NumericArray<Type> NumericArray<Type>::operator *(double factor) const
{
NumericArray<Type> output(NumericArray<Type>::Size());
for(int i=0; i<Array::Size(); i++)
{
output[i] = (*this)[i] * factor;
//return output;
}
return output;
}
June 19th, 2012 02:16 PM
#14
Re: generic inheritance
I find that I implement operator * in Array and NumericalArray
June 19th, 2012 02:17 PM
#15
Re: generic inheritance
Originally Posted by
oteel
I doing what other doing I mean classmates))) If serious, I thinks main purpose of separating is that show new combination of pre processors... like including array.cpp in main not array.h like in class exercises
That is not how templates work, and that is the reason why you're getting a linker error.template classes , all the code must be in one source file. That is wrong . If anything, you would #include NumericArray.cpp within NumericArray.h.
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Originally Posted by oteel
Vlad - MS MVP [2007 - 2012] - 
perator*(double)const " (??D?$Array@VPoint@@@@QBE?AV0@N@Z)
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