#include <iostream>
#include "memory"
// base class
class base
{
public:
void setVal(int val)
{
m_val = val;
}
int getVal()
{
std::cout << "val = " <<m_val<<std::endl;
return m_val;
}
bool checkVal(int val)
{
return val>8?true : false;
}
private:
int m_val = 5;
};
// derived class
class derived1: public base
{
private:
};
// derived class
class derived2: public base
{
public:
bool checkd2Val()
{
checkVal(9);
}
private:
};
int main()
{
std::unique_ptr<base> d1;
d1 = std::make_unique<derived1>();
std::unique_ptr<base> d2;
d2 = std::make_unique<derived2>();
d2->checkd2Val(7);
return 0;
}
The compilor gives error that says: No member named "checkd2Val" in base.
I am wondering how do we call checkd2Val in this case? Thanks!!
2
The error is correct. You are trying to call checkd2Val() using a base* pointer, and checkd2Val() does not exist in the base class.
If you really need to call checkd2Val() with d2 then you need to type-cast it, eg:
static_cast<derived2*>(d2.get())->checkd2Val(7);
However, this will still fail, because derived2::checkd2Val() does not accept an input parameter but main() is passing in a value.
You should consider instead to declare base::checkVal() as virtual and have derived2 override it, eg:
#include <iostream>
#include <memory>
// base class
class base
{
public:
void setVal(int val)
{
m_val = val;
}
int getVal()
{
std::cout << "val = " <<m_val<<std::endl;
return m_val;
}
virtual bool checkVal(int val)
{
return val > 8;
}
private:
int m_val = 5;
};
// derived class
class derived2: public base
{
public:
bool checkVal(int val) override
{
return base::checkVal(9);
}
};
int main()
{
std::unique_ptr<base> d2 = std::make_unique<derived2>();
d2->checkVal(7);
return 0;
}
0