private variables in functions

[iandalton9690]

without getting too into it, i need to access a private variable to use that number in a calculation. i have a function to return it, my question becomes if I call

int PVreturn()
{
return privateVariableName
};

is this something that I can drop into a math equation?
example:

int PvMaths()
{
int newvariable
newvariable = PVreturn() + 6
};

if not what's the best way I could do that?

[giblit]

If they are in two different classes then a getter should be fine if not you should just access the private directly. Or, if it is inherited then protected would be best.

[Peter87]

giblit wrote:

if it is inherited then protected would be best.

Not necessarily. You might want to protect your members from accidental modifications in subclasses just as you do with other classes.

[iandalton9690]

The function is in an inherited class, the variable is in the base class as a private variable.

and thats exactly what i'm hoping for by keeping it private, that I won't accidentally modify it somewhere.
long story short I'm writing a program to simulate a bank account / atm, and this formula is going to be used to calculate the interest rate of the bank account.

however to do so the account balance variable is in a publicly accessed class as a private variable. I have a public function just like above that does a return on the variable but I'm wondering if that's enough? It doesn't seem to work when I use it in another program i'm using just to test functions

also I haven't learned about protected yet in my class, so I don't know if I can do that

I don't really know what I'm doing, so in a test function to see if I could I did this. it built and ran successfully but returned math as a value of 0.

#include <iostream>
#include <iomanip>

using namespace std;
int math;
int value = 10;
int balance = 100;

int returnmath()
{
return value;
};

int main ()
{ 


	math == returnmath() * balance;
		cout << math << endl;
	

	system ("pause");
}

edit: sorry. i'm an idiot with the ==.

[shadowCODE]

Use BaseClass::getFunction() to get the private data from the base class while in the derived class.
e.g

class BaseClass
{
public:
   int getFunction()
   {
      return value;
   }
private:
   int value;
};

class DerivedClass : public BaseClass
{
 public:
   int someFunction()
  {
       return BaseClass::getFunction() + someOtherStuff();
  }
};

Accessing the private value member of the base class via the
BaseClass::getFunction() call keeps the private data member in the base class free from being corrupted later and of course is accessible by rules governing inheritance hierarchies.