what does "const" mean when overloading operator in C++

Question

I saw something like:

const char& operator[] (int Index) const

the first const I understand. It's to protect the returning char from being modified.

But what does second const mean? Why do we sometimes use two const, sometimes just one?

See also http://stackoverflow.com/questions/19237411/const-and-non-const-operator-overloading?rq=1 — Mat, Mar 17 '14 at 16:31

score 7 · Accepted Answer · answered Mar 17 '14 at 16:29

7

It can be used for any member function, not only operators. It means, that this function will:

answered Mar 17 '14 at 16:29

Kiril Kirov

2

I always like to say it's the way to specify the constness of the implicit `this` pointed to object. – StoryTeller - Unslander Monica Mar 17 '14 at 16:31
do the mutable ones mean local variables in side the function? – Yiou Mar 17 '14 at 16:35
@user3429675 - no, they are regular data members, that can be changed in `const` functions. `mutable` is a keyword, like `const` for example. A mutable data member could be: `mutable int x;` for example. – Kiril Kirov Mar 18 '14 at 07:39

1 Answers1