CODEWITHSUNDEEP
c++
T M
T M

Reputation: 3315

c++ why I do not get compile error when I call non const method from ref member inside const method

why I can call non const method from ref member inside const method? I am expected to get compile error like in case if m_a were not reference type. run on http://cpp.sh/

// Example program
#include <iostream>

class A
{
    public:
    void nonConstMethodOfA()
    {
        std::cout << "nonConstMethodOfA is called" << "!\n";
    }
};

class B
{
    public:
    B(A& a)
    : m_a(a)
    {
        constMethodOfB();
    }

    private:
    A& m_a;
    void constMethodOfB() const
    {
        m_a.nonConstMethodOfA();
    }
};

int main()
{
  A varA;
  B varB(varA);
}

Upvotes: 2

Views: 84

Answers (2)

lorro
lorro

Reputation: 10880

Const member function means your this will point to a const object, thus this->fn() can only be called if fn() is const. It doesn't lock the type, nor any similar-typed input parameters or globals. You can, however, specify those as const as well if you wish.

Upvotes: 1

Richard Hodges
Richard Hodges

Reputation: 69864

const A & means "a reference to a const A"

A & means "a reference to a mutable A"

A reference cannot be reassigned, so A & also implicitly means "a const reference to a mutable A".

Upvotes: 2

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