Some simple organization questions.

[twentytortures]

So I'm still pretty new to C++ and have a few questions.

I don't like how all the irrlicht examples are organized. I prefer to have my projects broken up into different functions and files. When trying to do this to some irrlicht examples I have problems when trying to pass variables into functions.

My question:
Would it be bad to use a lot of global variables? At the moment I only have two globals. Would it be bad if I made the majority of my irrlicht related things declared globally?

Thanks.

EDIT: Also, how do I display a number as a string? Do I have to convert it to a string?

[Delee]

What problems do you have passing variables to functions?

It is generally considered bad practice to have a lot of global variables. There are many memory problems involved. In the end, it depends on your organisation of the program - sometimes, you cannot avoid a few global variables. In C++, I think it is common to use data structures to store information and pass a reference to that.

[twentytortures]

It's kind of hard for me to describe. Do you know of any examples that shows something like example 4 organized into separate functions?

[Rytz]

It's kind of hard for me to describe. Do you know of any examples that shows something like example 4 organized into separate functions?

One approach would be to create pointers to all of the objects created in "main" in the "MyEventReceiver" class.

That way when you create a "MyEventReceiver" object you can reference all of your different Irrlicht objects by just passing around the "MyEventReceiver" object (pointer).

Whether this is good design or not is up for speulation I guess. If you're not catching my drift I can show you an example.

[Delee]

Not really... for examples I generally prefer everything to be in one function as it is easier to follow. Do you have problems passing Irrlicht objects?

Code: Select all

IrrlichtDevice *device       = createDevice(EDT_DIRECT3D9, dimension2d<s32>(640, 480), 16, false, false, false, &receiver);
IVideoDriver   *videoDriver  = device -> getVideoDriver();
ISceneManager  *sceneManager = device -> getSceneManager();

DoSomething(device, videoDriver, sceneManager);

-

void DoSomething(IrrlichtDevice *device, IVideoDriver *videoDriver, ISceneManager *sceneManager) {
	...
}

Or ...

Code: Select all

vector3df veloc    = ...;
matrix4   position = ...;

Create(veloc, position);

-

void Create(vector3df velocity, matrix4 position) {
	...
}

I hope that helps you out... it is hard to give specific examples without knowing what the problem is.

[hybrid]

Better use 'const vector3df&' to avoid passing by copy, though this is only a little performance overhead, no real loss of functionality.

[twentytortures]

I usually like to pass data into variables by using a '&' pointer like this:

Code: Select all

void someFunction(int &a)
{
     a = 2;
}

Rather than do it this way:

Code: Select all

int someFunction()
{
     int a;
     a = 2;
     return a;
}

But irrlicht objects are declared using the '*' pointer, does this still work the same way? I.e. would this function work the same as the one above?:

Code: Select all

void someFunction(int *a)
{
     a = 2;
}

I can post a more specific example when I have some more free time.

[Acki]

yes it works this way, but you have to do it this way:

Code: Select all

void someFunction(int *a)
{
     &a = 2;
}

otherwise you set the pointer (int*) to point to the address 2 and not set the value to 2 !!!

[CuteAlien]

yes it works this way, but you have to do it this way

tss, tss... *slaps Acki* - this way is the wrong way ;-)

[roxaz]

i always use this and it works perfect

Code: Select all

void someFunction(int *a) 
{ 
     a = 2; 
}

[thephoenix]

Code: Select all

void someFunction(int *a)
{
     *a = 2;
}

That should be right.

[roxaz]

thephoenix no. pointer value is adress in a memmory. *a = 2; makes a to point to adress 2 in a memmory and this adress is not valid. do not do that at home

[Luben]

no, *a=2 means (the memory value pointed to by a) = 2.

[thephoenix]

Huh?

I definately wanted to do what Luben said.
roxaz:
*var <- that's dereferencing, the same is done by class->somefunction(), which can be written (*class).somefuntion()
With that you'll sure change the value, and not the pointer.
I mean, that's what *I* am using, I don't know your Compiler

[roxaz]

aaaaaa..... whatever. as long as it works for me good there is no problem