Need help finishing two operator overloading functions

**AmirHossein H-m** · 04-27-2013

I am wondering can some help to finish these two remaining operator overloading functions

Also, "contents and NumItems are private"

Thanks

Code:

Bag operator+ (const Bag& b1, const Bag& b2);
//Postcondition: the bag returned is the union of b1 and b2.


ostream& operator<<(ostream&, const Bag&);
//Overloading operator <<

DynBag.cpp

Code:

#include <stdexcept>
#include <iostream>
#include "DynBag.h"




Bag::Bag(int InitialCapacity) : NumItems(0)
{
    capacity = InitialCapacity;
    contents = new ItemType[capacity];
}


Bag::Bag(const Bag& other) : NumItems(other.NumItems)
{
    capacity = other.capacity;
    contents = new ItemType[capacity];
    for (int i=0; i < NumItems; ++i)
        contents[i] = other.contents[i];
}




int Bag::size () const
{
    return NumItems;
}


int Bag::count_duplicates (const ItemType& target) const
{
    int answer = 0;


    for (int i = 0; i < NumItems; ++i)
        if (target == contents[i])
            ++answer;
    return answer;
}


void Bag::insert(const ItemType & entry)
{
    if (NumItems >= capacity)
        reserve(capacity*2);


    contents[NumItems] = entry;
    ++NumItems;
}


void Bag::erase_one(const ItemType & target) throw(domain_error)
{
    int i, j;


    for (i = 0; i < NumItems; ++i)
        if (target == contents[i]) break;


    if (i == NumItems) throw domain_error("Target Not Found");


    if (i < NumItems-1) // target found but not last element
        for (j = i; j < NumItems-1; ++j)  // shift things up
            contents[j] = contents[j+1];


    --NumItems;


}






int Bag::erase(const ItemType & target)
{
    int count = count_duplicates(target);
    int removed = 0;


    for ( ; removed < count; ++removed)
        erase_one(target);


    return(removed);


}


Bag& Bag::operator =(const Bag& other)
{
    if (&other == this) return *this;


    delete[] contents;
    NumItems = other.NumItems;
    capacity = other.capacity;
    contents = new ItemType[capacity];
    for (int i=0; i < NumItems; ++i)
        contents[i] = other.contents[i];
    return *this;
}


void Bag::reserve (int new_capacity)
{
    if (new_capacity == capacity) return;


    if (new_capacity < NumItems) new_capacity = NumItems;


    ItemType *new_contents = new ItemType[new_capacity];


    for (int i=0; i < capacity; ++i)
        new_contents[i] = contents[i];


    delete[] contents;
    contents = new_contents;
    capacity = new_capacity;
}


void Bag::print(ostream& out) const
{
    for (int i = 0; i < NumItems; i++)
        out << contents[i] <<"\t";


    out <<endl;


}


Bag operator+ (const Bag& b1, const Bag& b2)
{




}


ostream& operator<<(ostream&, const Bag&)
{


}

DynBag.h

Code:

#ifndef DYNBAG_H
#define DYNBAG_H


#ifndef  _STRING_H_
#include <string>
#endif


using namespace std;


typedef string ItemType;


class Bag {


    public:


    Bag (int InitialCapacity);


    Bag(const Bag& other);


    ~Bag();


    void insert(const ItemType& entry);


    void erase_one(const ItemType& target) throw (domain_error);


    int erase(const ItemType& target);




    Bag& operator=(const Bag& other);
    //Postcondition: Each item in other has been copied to this bag.


    Bag& operator+=(const Bag& addend);
    //Postcondition: Each item in addend has been added to this bag.


    void reserve(int new_capacity);
    //Postcondition: The bag's current capacity is changed to the new
    //capacity.


    //CONSTANT MEMBER FUNCTIONS


    int size() const;
    //Postcondition: the return value is the number of items in the Bag.


    int count_duplicates (const ItemType& target) const;
    //Poscondition: the return value is the number of times that target is
    //in the bag.




    void print (ostream& out) const;
    //Postcondition: The contents of the bag are written to standard
    //output.


    private:
        ItemType *contents;
        int NumItems;
        int capacity;
};


Bag operator+ (const Bag& b1, const Bag& b2);
//Postcondition: the bag returned is the union of b1 and b2.


ostream& operator<<(ostream&, const Bag&);
//Overloading operator <<


#endif

**grumpy** · 04-27-2013

Given that you have an operator+=(), even though you haven't shown the definition, the definition of operator+() should be easy.

Code:

Bag operator+(const Bag &b1, const Bag &b2)
{
     Bag retval(b1);    // relies on a working copy constructor
     retval += b2;       // uses your operator+=()
     return retval;       //   relies on copy constructor being accessible
}

The operator<<() would presumably need to have a loop that outputs each element in the bag, sequentially. It can probably call the print() member function.

**AmirHossein H-m** · 04-27-2013

Originally Posted by grumpy

Given that you have an operator+=(), even though you haven't shown the definition, the definition of operator+() should be easy.

Code:

Bag operator+(const Bag &b1, const Bag &b2)
{
     Bag retval(b1);    // relies on a working copy constructor
     retval += b2;       // uses your operator+=()
     return retval;       //   relies on copy constructor being accessible
}

The operator<<() would presumably need to have a loop that outputs each element in the bag, sequentially. It can probably call the print() member function.

Didn't work and getting these errors:

http://s23.postimg.org/jq8h1548r/Untitled.jpg

this is my main:

Code:

#include <stdexcept>
#include <iostream>
#include "DynBag.h"


int main ()
{
	Bag b(2), b1(3), b2(2), b3(4);


	b.insert("Lidiecita");
	b.insert("Brendita");
	b.insert("Francisquito");
	b.insert("Lidiecita");
	b1.insert("Mayi");
	b1.insert("Eimy");


	b += b;
	b.print(cout);


	b3 = b + b1;
	b3.print(cout);


	b2 = b1;
	b2.print(cout);


	Bag b4 = b3;
	cout << b4;
}

**laserlight** · 04-27-2013

Originally Posted by AmirHossein H-m

Didn't work and getting these errors:

http://s23.postimg.org/jq8h1548r/Untitled.jpg

You should be able to copy and paste the error messages from the IDE and post them here in [code][/code] bbcode tags. As it stands, your image is so small that the text is unreadable.

Don't do this:

Code:

#ifndef  _STRING_H_
#include <string>
#endif

There will be a header inclusion guard in <string>, so let it do its job.

Don't do this:

Code:

using namespace std;

This is a header file, so there should be no using directives at file scope as they will then affect the source files in which this header is included.

**laserlight** · 04-27-2013

Originally Posted by AmirHossein H-m

Didn't work and getting these errors:

http://s23.postimg.org/jq8h1548r/Untitled.jpg

You should be able to copy and paste the error messages from the IDE and post them here in [code][/code] bbcode tags. As it stands, your image is so small that the text is unreadable.

Don't do this:

Code:

#ifndef  _STRING_H_
#include <string>
#endif

There will be a header inclusion guard in <string>, so let it do its job.

Don't do this:

Code:

using namespace std;

This is a header file, so there should be no using directives at file scope as they will then affect the source files in which this header is included.

**AmirHossein H-m** · 04-28-2013

Originally Posted by laserlight

You should be able to copy and paste the error messages from the IDE and post them here in [code][/code] bbcode tags. As it stands, your image is so small that the text is unreadable.

Don't do this:

Code:

#ifndef  _STRING_H_
#include <string>
#endif

There will be a header inclusion guard in <string>, so let it do its job.

Don't do this:

Code:

using namespace std;

This is a header file, so there should be no using directives at file scope as they will then affect the source files in which this header is included.

Thanks , But my problem didn't solve ...

**laserlight** · 04-28-2013

Because you have not posted your updated code and corresponding error messages.

**AmirHossein H-m** · 04-28-2013

Code:

C:\Users\Amir.Asus\Documents\assi6\DynBag.cpp||In function 'std::ostream& operator<<(std::ostream&, const Bag&)':|
C:\Users\Amir.Asus\Documents\assi6\DynBag.cpp|124|warning: no return statement in function returning non-void [-Wreturn-type]|
obj\Debug\Documents\assi6\Driver.o||In function `main':|
C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|18|undefined reference to `Bag::operator+=(Bag const&)'|
C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|21|undefined reference to `Bag::~Bag()'|
C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|28|undefined reference to `Bag::~Bag()'|
C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|28|undefined reference to `Bag::~Bag()'|
C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|28|undefined reference to `Bag::~Bag()'|
C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|28|undefined reference to `Bag::~Bag()'|
obj\Debug\Documents\assi6\Driver.o:C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|28|more undefined references to `Bag::~Bag()' follow|
obj\Debug\Documents\assi6\DynBag.o||In function `ZplRK3BagS1_':|
C:\Users\Amir.Asus\Documents\assi6\DynBag.cpp|117|undefined reference to `Bag::operator+=(Bag const&)'|
C:\Users\Amir.Asus\Documents\assi6\DynBag.cpp|118|undefined reference to `Bag::~Bag()'|
||=== Build finished: 9 errors, 1 warnings (0 minutes, 0 seconds) ===|

main.cpp

Code:

#include <stdexcept>
#include <iostream>
#include "DynBag.h"


int main ()
{
    Bag b(2), b1(3), b2(2), b3(4);


    b.insert("Lidiecita");
    b.insert("Brendita");
    b.insert("Francisquito");
    b.insert("Lidiecita");
    b1.insert("Mayi");
    b1.insert("Eimy");


    b += b;
    b.print(cout);


    b3 = b + b1;
    b3.print(cout);


    b2 = b1;
    b2.print(cout);


    Bag b4 = b3;
    cout << b4;
}

DynBag.cpp

Code:

#include <stdexcept>
#include <iostream>
#include "DynBag.h"




Bag::Bag(int InitialCapacity) : NumItems(0)
{
    capacity = InitialCapacity;
    contents = new ItemType[capacity];
}


Bag::Bag(const Bag& other) : NumItems(other.NumItems)
{
    capacity = other.capacity;
    contents = new ItemType[capacity];
    for (int i=0; i < NumItems; ++i)
        contents[i] = other.contents[i];
}




int Bag::size () const
{
    return NumItems;
}


int Bag::count_duplicates (const ItemType& target) const
{
    int answer = 0;


    for (int i = 0; i < NumItems; ++i)
        if (target == contents[i])
            ++answer;
    return answer;
}


void Bag::insert(const ItemType & entry)
{
    if (NumItems >= capacity)
        reserve(capacity*2);


    contents[NumItems] = entry;
    ++NumItems;
}


void Bag::erase_one(const ItemType & target) throw(domain_error)
{
    int i, j;


    for (i = 0; i < NumItems; ++i)
        if (target == contents[i]) break;


    if (i == NumItems) throw domain_error("Target Not Found");


    if (i < NumItems-1) // target found but not last element
        for (j = i; j < NumItems-1; ++j)  // shift things up
            contents[j] = contents[j+1];


    --NumItems;


}






int Bag::erase(const ItemType & target)
{
    int count = count_duplicates(target);
    int removed = 0;


    for ( ; removed < count; ++removed)
        erase_one(target);


    return(removed);


}


Bag& Bag::operator =(const Bag& other)
{
    if (&other == this) return *this;


    delete[] contents;
    NumItems = other.NumItems;
    capacity = other.capacity;
    contents = new ItemType[capacity];
    for (int i=0; i < NumItems; ++i)
        contents[i] = other.contents[i];
    return *this;
}


void Bag::reserve (int new_capacity)
{
    if (new_capacity == capacity) return;


    if (new_capacity < NumItems) new_capacity = NumItems;


    ItemType *new_contents = new ItemType[new_capacity];


    for (int i=0; i < capacity; ++i)
        new_contents[i] = contents[i];


    delete[] contents;
    contents = new_contents;
    capacity = new_capacity;
}


void Bag::print(ostream& out) const
{
    for (int i = 0; i < NumItems; i++)
        out << contents[i] <<"\t";


    out <<endl;


}


Bag operator+(const Bag &b1, const Bag &b2)
{
     Bag retval(b1);    // relies on a working copy constructor
     retval += b2;       // uses your operator+=()
     return retval;       //   relies on copy constructor being accessible
}


ostream& operator<<(ostream&, const Bag& b)
{


}

DynBag.h

Code:

#ifndef DYNBAG_H
#define DYNBAG_H




#include <string>




using namespace std;


typedef string ItemType;


class Bag {


    public:


    Bag (int InitialCapacity);


    Bag(const Bag& other);


    ~Bag();


    void insert(const ItemType& entry);


    void erase_one(const ItemType& target) throw (domain_error);


    int erase(const ItemType& target);




    Bag& operator=(const Bag& other);
    //Postcondition: Each item in other has been copied to this bag.


    Bag& operator+=(const Bag& addend);
    //Postcondition: Each item in addend has been added to this bag.


    void reserve(int new_capacity);
    //Postcondition: The bag's current capacity is changed to the new
    //capacity.


    //CONSTANT MEMBER FUNCTIONS


    int size() const;
    //Postcondition: the return value is the number of items in the Bag.


    int count_duplicates (const ItemType& target) const;
    //Poscondition: the return value is the number of times that target is
    //in the bag.




    void print (ostream& out) const;
    //Postcondition: The contents of the bag are written to standard
    //output.


    private:
        ItemType *contents;
        int NumItems;
        int capacity;
};


Bag operator+ (const Bag& b1, const Bag& b2);
//Postcondition: the bag returned is the union of b1 and b2.


ostream& operator<<(ostream&, const Bag& b1);
//Overloading operator <<


#endif

It would be great if you could help me finish

Code:

Bag operator+ (constBag& b1, constBag& b2);
ostream& operator<<(ostream&, constBag& b1);

Thank you ...

**laserlight** · 04-28-2013

This error message is telling you that your definition of operator<< is incompletely, and indeed the body of that function is empty:

Code:

C:\Users\Amir.Asus\Documents\assi6\DynBag.cpp||In function 'std::ostream& operator<<(std::ostream&, const Bag&)':|
C:\Users\Amir.Asus\Documents\assi6\DynBag.cpp|124|warning: no return statement in function returning non-void [-Wreturn-type]|
obj\Debug\Documents\assi6\Driver.o||In function `main':|

This error message is telling you that you did not define operator+= at all:

Code:

C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|18|undefined reference to `Bag::operator+=(Bag const&)'|

This error message is telling you that you did not define the destructor:

Code:

C:\Users\Amir.Asus\Documents\assi6\Driver.cpp|21|undefined reference to `Bag::~Bag()'|

**Elysia** · 04-28-2013

Also, if possible, use std::vector instead of new.

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