Using const before the returned type.

Question

Why are using a classifier const before the returned type Date in the next code snippet:

...
const Date &Date::operator+=(int additionalDays) {
for (int i = 0; i < additionalDays; i++)
helpIncrement();
return *this;
}
..?

Answer 1

const "freezes" the value of the variable, prwventing it from further change and ensuring that it remains the same

Answer 2

generally spoken, you use const always to protect the variable (so it will not be changed).
in this case you return a reference, so it would lead to unexpected behaviour if you do not make it const! (why,? wrong question! what does reference mean ;))

Answer 3

Thanks, but it's wrong answer ;), because in other places of the code const before Date don't used:

Date &Date::operator++() {
helpIncrement();
return *this;
}

Answer 4

I am right ;)

https://code.sololearn.com/cZ6VOslmWLg1/?ref=app

Answer 5

Output https://code.sololearn.com/cZ6VOslmWLg1/?ref=app:

2 member: 2
3 member: 3

... are you sure?

Answer 6

The use of the constant did not affect

Answer 7

I updated the examle,
hope it is now more clear.

at this point I would explain it more extensively, but you don't trust me anyway or don't want to look up what reference means...

[edit] if you get confused with the test variables, just play with the code and see what happens ;)

[edit2] what just came to my mind, do you struggle to understand the operators itself?
I don't know your level of experience...