iterator of map | ++ vs += 1

Question

Refer code below:
https://www.sololearn.com/en/compiler-playground/c4K0LmgGspgf

It works fine and just curious why itr++ works but changing it to itr = itr + 1 into for loop does not work?

Answer 1

It is because of operator overloading.

The itr++, ++itr, and itr+=n operators have been specifically overloaded to advance iterators.

However, itr = itr + 1 only works if the iterator is a basic pointer. For any more complex iterator, basic math operations are undefined.

This is similar to how the + operator is overloaded to do addition for numbers, but also do concatenation for strings.

Answer 2

I meant itr+=n as the += operator.
The n is there to represent any number.
itr+=1 is the same as itr++ and ++itr in that they all advance the iterator once.

But you can also use other numbers to advance the iterator further.
itr+=2 would advance the iterator 2 spots.

Answer 3

Thanks a lot..!

I got your point except overloading of itr+=n?

Do you mean itr += 1 and itr+=n is a different overloaded function? Is this possible?

I am clear that itr++ and ++itr is overloaded and makes sense. +n version is confusing to me. It would be good to know more on this

Answer 4

Thanks