Stack overflow when declaring array

[laserlight]

Are they the same?

Effectively, since the second version is likely to be optimised to the first, but if I am not wrong, in theory the second version involves default construction of a temporary and then copy construction of my_class.

And is the only difference that if I wanted to have a constructor with parameters, I could use the latter to initialize some variables?

No, you can directly initialise with arguments, e.g.,

MyClass my_class(x, y, z);