protected members are not accessible through a pointer or object

Question

I have 2 classes Training and Testing, where Training is the base class and Testing is the derived class of Training.

I have Testing class member function, float totalProb(Training& classProb, Training& total), which takes 2 parameters, both are Training class objects. The code:

void Testing::totalProb(Training& classProb, Training& total) {

    _prob = (_prob * ((float)(classProb._nOfClass) / total._tnClass));
    cout << "The probalility of the " << it->first << " beloning to " << classProb._classType << " is: " << _prob << endl;
}

Basically what this function does is calculate the probability of each document in test1 (an object of Testing class) belonging to class1 (an object of Training class).

All the Training class (which is the base class) variables are Protected and all the Training class functions are Public.

When I try to run test1.totalProb(class1, total); I get the error Error C2248 'Training::_probCalc': cannot access protected member declared in class 'Training'. I am unable to get around this.

Answer 1

You are trying to access the member of an other instance of your mother class: classProb, but inheritance make you able to access protected member of your own parent class only.

One way to correcting (but it strongly depend of what you are trying to do) is to put an getter of _probClass in your Training class and call it in your test, for instance for the _probCalc member:

public:
  (Type) Training::getProbCalc() {
    return _probCalc;
  }

the to change your call in the loop:

for (it3 = classProb.getProbCalc().begin(); it3 != classProb.getProbCalc().end(); it3++)

If you are trying to acces your own member inherited by your mother instance just call them directly. For instance:

for (it3 = _probCalc().begin(); it3 != _probCalc().end(); it3++)