simple question about objects ,pointers and memory allocation

[go for it]

i've recently asked the same question and didn't get a good answer so ill be asking it again with some edits
why they always use
class_name *pointer = new class_name(arg)
pointer->member()

instead of
class_name object = new class_name(arg)
object.member()

im sorry im learning c++ after c# which makes this kinda confusing to me
the first we create pointer to a new object then we use it to access member/method
the second we create the object striaght then use it directly

what is the difference ? do i got it right ? which is more efficient ?
which expression in c++ create in heap and which create in stack ? and which is better or what is the use of both ?

[coder777]

there's no difference apart from using -> vs .

in c# any non trivial type will be allocated on the heap (and automatically free'd by the garbage collector). with c++ you can decide whether an object is created in heap or stack.

heap:

class_name *pointer = new class_name(arg)
pointer->member()

stack:

class_name obj(arg); // This is a local variable which is destroyed when the function ends
obj.member()

the second we create the object striaght then use it directly

what is this 'directly'? it's only a convention

which is more efficient ?

stack is faster

which expression in c++ create in heap and which create in stack ?

heap: lifetime of the object exceeds the current function
stack: local variable / only valid within the function

[Nobun]

Sorry to correct in part the reply of coder777... I know I am not a programmer, but he didn't notice a thing.

The original question said:

> why they always use
> class_name *pointer = new class_name(arg)
> pointer->member()
>
> instead of
> class_name object = new class_name(arg)
> object.member()

As far as I know the second form is completely wrong. "new" operator allocates memory for a new object, and return the memory address of that object (so it returns a POINTER).
The object will survive until it will destroyed with "delete".

The correct way to create a local object (a true object to be used through value) is another one, and that one showed by coder777

class_name obj(arg); // This is a local variable which is destroyed when the function ends
obj.member()

This form is the correct way to create a "real" object to be used directly (without need to be dereferenced with ->). This object will be local, so it will be destroyed when fuction will end.

All things said by coder777 are right, however