Why separate variable definition and initialization in C++?

Question

I\'m currently working on some quite old C++ code and often find things like

int i;
i = 42;

or

Object* someObject = NULL;
someO         


        

Answer 1

Why separate variable definition and initialization in C++?

You haven't separated definition and initialization. You have just assigned the variable/object (to some particular) value in your code snippet. So the title is misleading.

Object someObject;
someObject = getTheObject();

is quite different from Object someObject = getTheObject();

someObject = getTheObject(); invokes the assignment operator of Object class whereas in Object someObject = getTheObject(); copy constructor of the class gets invoked. This is also known by the name copy initialization

A good compiler might generate the same code in case of int i; i = 42; and int i =42. There won't be much of an overhead.

BTW I always prefer int i = 42 to int i; i=42 and

Object someObject = getTheObject(); to

Object someObject; someObject = getTheObject();

P.S : int i = 42 defines and initializes i whereas int i; i=42 defines i and then assigns 42 to it.