printing out subclass objects and int sega int nintendo bool enjoy and string fun

[sonicflare9]

how can I do that? please help

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

template<class gamer>
class game
{
private:

protected:
	int nintendo;
	int sega;
	string fun;
	bool enjoy;
public:

};

template<class gamer>
class cookies : public game<gamer> {
public:
	cookies() {}
	cookies(std::string description)
		: description(description)
	{ }

	std::string description;
};
int main()
{    
	template<class gamer>
	std::vector<cookies> vec(5);
	template<class gamer>
	vec[0] = cookies("Tasty");
	template<class gamer>
	vec[1] = cookies("Delicious");
	template<class gamer>
	vec[2] = cookies("Yummy");
	template<class gamer>
	vec[3] = cookies("Hungry");
	template<class gamer>
	vec[4] = cookies("Full");

	return 0;
}

[laserlight]

Your code makes no sense to me at all. What on earth does a game class template model, and why does it have those four member variables? What does it all mean?

My suggestion is that you stop defining class templates. You almost certainly don't need it here. When you define your base class, think about what does it model, and declare the appropriate virtual member functions.

Here's a contrived example of "printing out subclass objects":

#include <iostream>
#include <ostream>
#include <vector>

class A
{
public:
    virtual void print(std::ostream& out) const
    {
        out << "This is an object of class A.";
    }

    virtual ~A() {}
};

std::ostream& operator<<(std::ostream& out, const A& obj)
{
    obj.print(out);
    return out;
}

class B : public A
{
public:
    virtual void print(std::ostream& out) const
    {
        out << "This is an object of class B, derived from class A.";
    }
};

class C : public A
{
public:
    virtual void print(std::ostream& out) const
    {
        out << "This is an object of class C, derived from class A.";
    }
};

int main()
{
    using namespace std;

    A a;
    B b;
    C c;
    vector<A*> items;
    items.push_back(&c);
    items.push_back(&b);
    items.push_back(&a);
    for (auto item : items)
    {
        cout << *item << endl;
    }
    // or if you cannot use the above loop:
    //for (vector<A*>::iterator iter = items.begin(); iter != items.end(); ++iter)
    //{
    //    cout << **iter << endl;
    //}
}

Notice that I declared A's destructor to be virtual, which is not important here but could matter when you use new and delete.

[sonicflare9]

i have to use template for the assignment

[laserlight]

i have to use template for the assignment

What exactly is your assignment, and why do you have to use a class template?

As it stands, it looks like you are not using the template meaningfully, so even if your assignment calls for the use of a template, if I were your instructor I would most certainly not be awarding you any marks merely for having random template syntax thrown into your code.

[Salem]

An Idiot's Guide to C++ Templates - Part 1 - CodeProject
Perhaps you should read more, rather than trying to learn through random typing.

[sonicflare9]

Classes & Objects
(Due
Tuesday
, April
24
th
at 11:59pm )
The goal
of this assignment is to build an application that consists of
a class
whose object values are assigned from a text fil
e
.
There will also be a subclass,
a vector and exception handling.
Include the following criteria:
Base Class
You are going to create a base class with the following criteria:
1)
Us
es
class templates so that the class can be used in
to handle
different
data
type
as required
.
2)
Name the class whatever you like
–
so long as it’s
a valid identifier and it’s
not offensive.
It doesn’t have to represent anything but you’re welcome to
come up with a theme if you like.
3)
The class will have the
following four protected
member variables
named
anything you like:
a.
A string
b.
Could be an int, float, or double
c.
Could be an int, float, or double
d.
A bool
4)
You will get the values for these member variables from a text file you
create. The details of the text file are as follows:
a.
Name
the text file whatever you like
b.
You must have five groups of the above base class members
meaning there will be 20 items in the text file
each group occupies
a line in the text file (5 lines for 5 groups)
.
i.
It is
recommend
ed
that you put each “record” of fo
ur on its
own line for clarity purposes.
ii.
For example, sample lines
in the file
would be:
Pie 3.1415 69 true
Apple 4.234 42 true
5)
Now, you are going to create a method in the base class that prints those
four members. So you’ll be required to set those mem
bers from the file
BEFORE you call the print function. More on this when the main() for the
program
will be explained
.
Subclass
You’re also going to have to make a subclass (derived class) of your base class
.
Follow the criteria below:
1)
Name this class wh
atever you like. You can make the name related to
the base class if you like.
2)
Inherit
this class publically from the base class.
3)
This class will only have ONE new
private
member variable and let’s
make it another string with a name of your choice.
4)
You will
NOT be getting the value of this string from the text file but
rather you can set the string to whatever you like when you create an
object of this subclass.
a.
That is, make a non
-
default constructor for this subclass with a
string as its only parameter and
then set the member string to
the value held in the constructor’s parameter.
5)
This class will have a print function as well that will be called from the
main using an object of this subclass.
a.
You CAN choose to call the print function of the base class
from
this function if you like.

Main Function
The following explains what you should have in the main function of your
program:
1)
You are going to create a vector of objects from the subclass NOT the
base class. You can call the vector anything you like.
2)
You a
re going to create five objects of the subclass. You can create
the objects however you like but remember to pass in a string as the
only parameter to each object’s constructor.
a.
Remember that when you create the objects of the subclass you
are going to con
struct the base class too and set the values of
its four member variables to the values in the text file.
b.
Again, how you do that and where is up to you.
3)
How you add the objects to the vector is up to you but remember our
vector example from class.
4)
You are
going to iterate through the vector and call the print function of
each subclass object, so that it prints the string in the subclass and the
four member variables in the base class.
a.
The format of the output is up to yo

Exception Handling
1)
The
only exception handling you
need
to have in this program deals with
accessing the file.
2)
If you are unable to read the file
–
for example, if it doesn’t exist, then you
should throw and exception and terminate the program.
3)
This is obviously going to occur
when you try to read the file so you have to
figure out where to handle this exception.
4)
This
WILL be testing for this and your file
will be deleted
and try to run your
program.
5)
You do not need to print anything out upon catching the exception, just terminate the program

[laserlight]

You should have done this as soon as the assignment instructions document was handed to you, but perhaps it is not too late: ask your instructor to explain what are the practical implications of "to handle different data type as required", e.g., does this mean that when the instruction says "Could be an int, float, or double", it means that this should be a template parameter so that the programmer using this class template can choose the type (although limited to this set of three), rather than you as the programmer writing the class template?

I recommend that you do this because other than that part, I see no use for a class template according to the other instructions. So, if it is not that part, then perhaps there was an oversight in the instructions. Alternatively, it could be that your instructor is incompetent and just wants you to have useless template syntax around to demonstrate that you know what template syntax looks like. As much as I would like to believe that your instructor is a good teacher rather than an incompetent one, the part of your instructions that require you to uselessly publicly inherit from a base class that should not be a polymorphic base class (or involve techniques outside of the OOP norm) makes me doubt it.

[sonicflare9]

what do i use try catch throw for the exception handling

[Guest]

Something like below.

try {
    // code that can throw
} catch (const std::exception& e) {
    std::cerr << e.what() << std::endl;
} catch (...) {
    std::cerr << "unknown exception" << std::endl;
}

Make sure you solve the other issues first though. If you haven't the slightest idea how to use templates yet your assignment expects it, then you must have not been paying any attention.

e.g., does this mean that when the instruction says "Could be an int, float, or double", it means that this should be a template parameter so that the programmer using this class template can choose the type

That's how I would interpret it. The class members are std::string, T, T, bool.

[sonicflare9]

try {
        throw = 20;
    }
    catch ()

sorry how do i fix

[Guest]

Ah, troll. GReaper or whoever said it was right. Can't believe people do this as a hobby.