C++ const in getter

Question

I\'m still learning about C++ and I\'m reading everywhere that I have to use const everywhere I can (for speed reason I think).

I\'m usually write my getter

Answer 1

const method informs compiler that you will not modify class instance on which this method is called:

class A {
public:
bool getReady() const {
    return ready;
}
};

so if you try to modify your object inside getReady() then compiler will issue error. Const methods are usefull where you have ie.: const A&, or const A*, then you can call only const methods on such objects.

as for:

const bool isReady() {
    return ready;
}

this const provides actually no real benefit, because bool is copied while isReady() returns. Such const whould make sense if returned type was a const char* or const A&, in such cases const makes your char string or A class instance immutable.