Help: what statement is this?

[daniele.g]

It is a very simple statement, nevertheless it makes me confused:

pcl::OpenNIGrabber grabber (device_id, depth_mode, image_mode);

Is it a function declaration? In case, why parameters have no type declared? Is it a function call?

Any clue?

Thanks in advance.
Daniele

 

[Stefan Ram]

It is a very simple statement, nevertheless it makes me confused:
pcl::OpenNIGrabber grabber (device_id, depth_mode, image_mode);

It is an expression statement (6.2).

 

[Victor Bazarov]

It is an expression statement (6.2).

Looks more like a declaration statement to me.

V

 

[Stefan Ram]

Looks more like a declaration statement to me.

Yes, you are right. I did not read careful enough. Sorry!

 

[Alf P. Steinbach]

It is a very simple statement, nevertheless it makes me confused:

pcl::OpenNIGrabber grabber (device_id, depth_mode, image_mode);

Is it a function declaration? In case, why parameters have no type
declared? Is it a function call?

Any clue?

It's a declaration of a variable (if device_id etc. are values) or a
function (if device_id etc. are types).

Assuming that it's a variable declaration:

The type of the variable is pcl::OpenNIGrabber.
The name is grabber.
The constructor arguments are device_id, depth_mode and image_mode.

Further assuming that this declaration compiles this means that the
pcl::OpenNIGrabber type is a class type that has at least one
constructor that takes 3 arguments, where the formal argument types can
accept the given arguments.

When the execution passes through the declaration the pcl::OpenNIGrabber
constructor is called with the given arguments, so the declaration
involves -- but isn't itself -- also a function call (a constructor is a
special function, and it's called here).

As a result of the constructor call an exception may be thrown here,
namely if the constructor fails.


Cheers & hth.,

- Alf

 

[Tobias Müller]

It is a very simple statement, nevertheless it makes me confused:

pcl::OpenNIGrabber grabber (device_id, depth_mode, image_mode);

Is it a function declaration? In case, why parameters have no type
declared? Is it a function call?

I guess it depends on the context.
- If device_id, depth_mode and image_mode are types, then it's a function
declaration.
- If they are variables, it's a variable declaration/definition (calling a
constructor with 3 arguments)

Maybe there are even more interpretations...

C++ is famous for such cases ;-)

Tobi

 

[Barry Schwarz]

It is a very simple statement, nevertheless it makes me confused:

pcl::OpenNIGrabber grabber (device_id, depth_mode, image_mode);

Is it a function declaration? In case, why parameters have no type declared? Is it a function call?

It appears to be a definition of an object named grabber which is of
type pcl::OpenNIGrabber with three values being passed to the
constructor.