When to use const in the beginning and in the end of a method declaration in C++

Question

When coding a header file in C++ with method declarations, what's the difference between:

int getFoo() const;

const int getFoo();

const int getFoo() const;

score 2 · Answer 1 · answered Mar 29 '16 at 21:40

2

First one, is for preventing this method changing any member variables of the object. Second one, is for the return type (ie: constant integer) Third one, is mix of both

answered Mar 29 '16 at 21:40

MIbrah

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The second `const T f() ` or `const T f() const ` is useless. – Mar 29 '16 at 21:47

score 0 · Accepted Answer · answered Mar 29 '16 at 21:46

Your first function operates on a const this pointer (that is; a const object that it can't change (or at least shouldn't)).

Your second function returns a constant integer - which is somewhat nonsensical since you can just assign it to a non-const variable and change it anyway. Besides, why does the function care if you change a POD type or not?

Your third function is just a combination of the first two. A function operating on a const object returning a const value.

When to use const in the beginning and in the end of a method declaration in C++

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