Classes - Adding members to members

[Daz]

Hi Everyone. Please could someone explain how I can go about adding
separate member functions to stock.add? For example,
stock.add.count(int) and stock.add.value(int)?

This way I can hopefully add to both 'cnt' and 'val'. This class
doesn't serve much of a purpose other than to help me learn about
classes (as this is my first).

Would I need to create another class, and add it as a friend to my
exisiting class? If so, what about the classes global variables?

Any help would be greatly appreciated as always. :o)

-----------------------------------CODE
START-----------------------------------------

#include <iostream>

using namespace std;
using std::string;
using std::cout;
using std::endl;

class stock
{
signed long int val;
long int cnt;
public:
stock () { val = 0; count = 0; };
stock (int a) { val = a; count = 0; }
void add (int a) { val = val + a; }
void subtract (int a) { val = val - a; }
signed int value() { return val; }

};

int main ()
{
stock pawn;
pawn.add(5);
pawn.add(6);
cout << pawn.value() << endl;
return 0;
}
-----------------------------------CODE
END-----------------------------------------

[Alf P. Steinbach]

* Daz:

Hi Everyone. Please could someone explain how I can go about adding
separate member functions to stock.add? For example,
stock.add.count(int) and stock.add.value(int)?

Use two member functions, one called add_count, and one called add_value.

--
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Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Daz]

Alf P. Steinbach wrote:

* Daz:

Hi Everyone. Please could someone explain how I can go about adding
separate member functions to stock.add? For example,
stock.add.count(int) and stock.add.value(int)?

Use two member functions, one called add_count, and one called add_value.

I thought I could make the member functions more elaborate, however,
your suggestion is certainly one I didn't think of.

Thanks for the prompt response Alf.

[Jonathan Lamothe]

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Daz wrote:

Hi Everyone. Please could someone explain how I can go about adding
separate member functions to stock.add? For example,
stock.add.count(int) and stock.add.value(int)?

This way I can hopefully add to both 'cnt' and 'val'. This class
doesn't serve much of a purpose other than to help me learn about
classes (as this is my first).

Would I need to create another class, and add it as a friend to my
exisiting class? If so, what about the classes global variables?

Any help would be greatly appreciated as always. :o)

-----------------------------------CODE
START-----------------------------------------

#include <iostream>

using namespace std;
using std::string;
using std::cout;
using std::endl;

class stock
{
signed long int val;
long int cnt;
public:
stock () { val = 0; count = 0; };
stock (int a) { val = a; count = 0; }
void add (int a) { val = val + a; }
void subtract (int a) { val = val - a; }
signed int value() { return val; }

};

int main ()
{
stock pawn;
pawn.add(5);
pawn.add(6);
cout << pawn.value() << endl;
return 0;
}
-----------------------------------CODE
END-----------------------------------------

Well, you could define your add function like this:

class stock
{

/* ... */

class
{
public:

void operator () (int a)
{
val = val + a;
}

/* define your member functions here */

} add;

/* ... */

};

This would keep the syntax you wanted, but you couldn't really call add
a function anymore. Hope that helps.

- --
Regards,
Jonathan Lamothe

/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/

die_if_kernel("Oops", regs, error_code);
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[Jonathan Mcdougall]

Daz wrote:

Hi Everyone. Please could someone explain how I can go about adding
separate member functions to stock.add? For example,
stock.add.count(int) and stock.add.value(int)?
In C++, a function call is denoted by adding parantheses after a name.
If a name has no parantheses after it, it is not a function call. In
your example,

stock.add.count();

"add" cannot be a function. However, you could make "add" an object in
"stock" and put a member function "count()" in "add".

class adder
{
public;
void count(int i);
void value(int i);
};

class test
{
public:
adder add;
void f();
};

int main()
{
test t;
t.f();
t.add.count(0);
}
Would I need to create another class, and add it as a friend to my
exisiting class?

No, friends are a different thing.
Jonathan

[Daz]

Jonathan Mcdougall wrote:
{

In C++, a function call is denoted by adding parantheses after a name. If a name has no parantheses after it, it is not a function call. In your example,

stock.add.count();

"add" cannot be a function. However, you could make "add" an object in "stock" and put a member function "count()" in "add".

class adder
{
public;
void count(int i);
void value(int i);
};

class test
{
public:
adder add;
void f();
};

int main()
{
test t;
t.f();
t.add.count(0);
}

}

Thanks for that Jonathan. Very useful, and very clever. I appreciate
the time you took to come up with a good working example, too. It's
very much appreciated.