Board index » cppbuilder » classes & inheritance...?

2005-04-20 10:23:30 PM
cppbuilder100
Hello,
This is a pretty basic question... :)
I've got a base class and an inheriting class...
class BaseClass
{
public:
void DoSomething();
private:
int BaseVar;
};
class MyBaseClass : public BaseClass
{
};
...so, when I call MyBaseClass::DoSomething() as it is inherited,
BaseClass::BaseVar is undefined. Is there a way to fix this easily with
"inherited" or "virtual" or the like?
Thanks so much!!!
Rob
 

"Robert G. Hoover" < XXXX@XXXXX.COM >writes:
 

The visiblities of both a function and a variable is controlled in the
same way by the public, protected and private cases.
The keyword virtual only applies to functions. It does not alter the
effect of public, protected and private.
class BaseClass
{
public:
void DoSomething();
private:
int BaseVar;
};
class MyBaseClass : public BaseClass
{
};
class BaseClass
{
public:
void DoSomething(); // visible to all
protected:
void DoSomethingElse(); // visible to descendent classes
private:
int BaseVar; // visible only to BaseClass
};
class MyBaseClass : public BaseClass
{
int int_var;
MyBaseClass()
{
DoSomething(); // ok
DoSomethingElse(); // ok
int_var = BaseVar; // no good, not visible
}
};
int main()
{
MyBaseClass mbc;
mbc.DoSomething(); // ok;
mbc.DoSomethingElse(); // no good, not visible
int x = mbc.BaseVar; // no good, not visible
return 0;
}
. Ed

{smallsort}

On Wed, 20 Apr 2005 10:23:30 -0400, Robert G. Hoover wrote:
--
Good luck,
liz
 

When I cursor over MyVar in the de{*word*81}, I see MyVar=????
What I've done here is to create MyBaseClass when Application->Run(). I am
not creating BaseClass. So, I have MyBaseClass running and I think when I'm
calling DoSomething(), it's referencing the MyVar in the BaseClass which is
uninitialized/undefined instead of (inherited and initialized) MyVar in
MyBaseClass.
Does this make more sense?
Thanks again!
Rob
____________________________________________________________________________
"Thomas Maeder [TeamB]" < XXXX@XXXXX.COM >wrote in message

"Robert G. Hoover" < XXXX@XXXXX.COM >writes:
MyBaseClass and BaseClass are classes. You "create" them staticly,
before the program even runs.
BaseClass. Why do you think that there are two different MyVars?
Could you please post *minimal* (i.e. just enough - not too little and
not too much) code so that others can see what you are seeing?