Why do you even need constructors?

Question

Why are constructors even a thing? You could just define a function and it would work the same. What is the use of a constructor?

Answer 1

Basically we want the object to be in a valid state as soon as you declare it. So as soon as you write e.g.

Dog waldo;

the waldo object is ready to go. You could write a .initialize function or so but if you forget to call it your program blows up.
Maybe it's more obvious with destructors; if you had to call all of them manually, C++ code would be a bugfest!
Almost every class will do something when a nw object is created, so we put that into the constructor.

Also it's just shorter to write of course, and more consistent. You don't do

int x;
x.initialize();

so why should you with classes?