CODEWITHSUNDEEP
c++operator-overloadingiostreammember-functions
Andy
Andy

Reputation: 137

The object has type qualifiers that are not compatible with the member function C++

std::ostream& operator<<(std::ostream&, const Course&);

void Course::display() {
    std::cout << std::left << courseCode_ << " | " << std::setw(20) << courseTitle_ << " | " << std::right
        << std::setw(6) << credits_ << " | " << std::setw(4) << studyLoad_ << " | ";
}

std::ostream& operator<<(std::ostream& os, const Course& a) {
    a.display();
    return os;
}

Problem occurs at the implementation of the ostream operator below a.display(). I don't see where the problem is, I have other codes that work with the same implementation.

error message:

The object has type qualifiers that are not compatible with the member function "sict::Course::display" object type is const sict::Course

Upvotes: 2

Views: 4343

Answers (1)

songyuanyao
songyuanyao

Reputation: 172864

In operator<<(), a.display(); fails because a is declared as const. You can't call non-const member function on it.

Course::display() should be declared as const member function, it's supposed to not modify anything.

void Course::display() const {
//                     ^^^^^
    ...
}

Upvotes: 9

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