Question

[Kmilano]

In my code, I used a global vector which a content of another vector will return in this global vector for using and calling in another part of my code.
when the inheritance is used, where I must introduce a global vector? is it possible that I introduce it in the base

[2kaud]

In my code, I used a global vector which a content of another vector will return in this global vector for using and calling in another part of my code.
when the inheritance is used, where I must introduce a global vector? is it possible that I introduce it in the base

Yes. A member of a base class can be accessed from a derived class (assuming access specifications allow). Also a static public member of a base class can be accessed from anywhere (although only one copy - not one per instance).

Consider

#include <iostream>
#include <vector>
using namespace std;

class B {
public:
	auto getb() {return b;}

	static vector<int> sb;	// Declaration only. Needs definition

protected:
	vector<int> b = {3, 4};
};

class D : public B {
public:
	auto getd() {return b;}
};

vector<int> B::sb = {4, 5};	// Definition

int main()
{
	D d;

	for (const auto& e : d.getd())
		cout << e << " ";

	cout << endl << endl;

	for (const auto& e : D::sb)
		cout << e << " ";

	cout << endl;
}

[Kmilano]

I used inheritance and object-oriented programming in c++ (visual studio)
I have a base class and some derived classes.
In the derived class, I defined some void function and inside them, one void function contained a vector for creating a matrix and other void function is contained a vector and some operation on 2 matrixes.
and I need to use a content of this matrix inside the second void function in this derived class, so for calling a content of this matrix I used a global vector and then I returned a result of that matrix inside a global vector, after that in the second void function, I called a global vector (instead of the vector which contains a matrix),


like the following example:

derived class:

//======first void function===========
void H::Mat(std::vector< std::vector<int> > &res){
....
}
ch=res;

//======2nd void function============
void H::multiplication(std::vector< std::vector<int> > &mul){
int a[];
...
mul= (ch[][]*a[]);

}

base class:

class base{
protected:
std::vector< std::vector<int> > ch;
std::vector< std::vector<int> > res;
std::vector< std::vector<int> > mul;

public:
virtual void H::Mat(std::vector< std::vector<int> > &res)=0
virtual void H::multiplication(std::vector< std::vector<int> > &mul)=0
}

I would like to know that is it correct that I put that global vector( std::vector< std::vector<int> > ch inside a private part in the base class to call in the derived class?

[2kaud]

ch, res and mul will be accessible to class base and its derived classes (assuming the derived classes are not inherited privately) - but not outside of these classes.

PS.

mul= (ch[][]*a[]);

Is an 'interesting' statement... but won't compile!