How to not inherit a variable in C++ classes

With C++ classes, you can have a derived class inherit a variable from its parent class. How can I define the derived class so that var2 is not inherited in derivclass?

class mainclass{
public:
    int var1;
    char var2;
    void test(){
        cout<<var1<<var2<<endl;
    }
}
class derivclass : mainclass{
public:
    void test(){
        cout<<var1<<var2<<endl;
        //want a compiler error here that var2 is not defined
    }
}