Pointer on Pointer, or simple Pointer?

[Heinz-Mario Frühbeis]

Hi,

can I use these functions as [1]?

[1]
Display* Dispplay_Open(){
return XOpenDisplay(NULL);
}

int Display_Close(Display *vDisplay){
return XCloseDisplay(vDisplay);
}

void Test(){
Display *nDisplay = NULL;
nDisplay = Display_Open();
Display_Close(nDisplay);
}

Or do I need to use a pointer on a pointer?

[2]
int Display_Close(Display **vDisplay){
return XCloseDisplay(*vDisplay);
}

void Test(){
Display *nDisplay = NULL;
nDisplay = Display_Open();
Display_Close(&nDisplay);
}

TIA
Heinz-Mario Frühbeis

[Ian Collins]

On 04/04/16 20:19, Heinz-Mario Frühbeis wrote:
> Hi,
>
> can I use these functions as [1]?
>
> [1]
> Display* Dispplay_Open(){
> return XOpenDisplay(NULL);
> }
>
> int Display_Close(Display *vDisplay){
> return XCloseDisplay(vDisplay);
> }
>
> void Test(){
> Display *nDisplay = NULL;
> nDisplay = Display_Open();
> Display_Close(nDisplay);
> }
>
> Or do I need to use a pointer on a pointer?
>
> [2]
> int Display_Close(Display **vDisplay){
> return XCloseDisplay(*vDisplay);
> }

Given XCloseDisplay() takes a Display*, why would you need a pointer to
pointer? The only reason to do this is if you are going to modify the
parameter value.

--
Ian Collins

[Heinz-Mario Frühbeis]

Ok, thanks.

Regards
Heinz-Mario Frühbeis