Different ways of initializing an object with default constructor

Question

class A {};

A a;// 1
A a{};// 2
A a = {};// 3
A a = A();// 4

There seems to be all options. Are 1, 2 and 3 are same and just the matter of style or there is some difference? 4 supposed to first create a temporary object and then assign it to an a, but it will happen only if I will turn off comliler's optimization completely, right?

I don't understand, what does your question have to do with Object Oriented Programming? — Thomas Matthews
– Thomas Matthews, Commented Jun 12, 2020 at 23:41
Supplementary reading on the options available: en.cppreference.com/w/cpp/language/initialization . Some entertaining viewing on just how deep the rabbit hole can go: youtube.com/watch?v=7DTlWPgX6zs — user4581301
– user4581301, Commented Jun 12, 2020 at 23:44
Note that starting with C++17, the 4th option does not actually create a temporary. In fact, it doesn't even require a move constructor be available (but C++14 does). — cdhowie
– cdhowie, Commented Jun 12, 2020 at 23:58
Initialization in C++ is more complicated than it should and has lot of corner cases. All your options might have different behaviors (but for your A, they are similar). — Jarod42
– Jarod42, Commented Jun 13, 2020 at 0:08

eerorika · Accepted Answer · 2020-06-12 23:41:38Z

2

Is different because it does default initialisation. This does not matter in case of A however, because there are no members to initialise.

answered Jun 12, 2020 at 23:41

eerorika

240k13 gold badges212 silver badges354 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Different ways of initializing an object with default constructor

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related