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Help with D3DXVECTOR2 pointers

Started by Mr Teatime May 3, 2003 at 11:40 AM 3 replies 700+ views

Original Post

May 3, 2003 at 11:40 AM

Looking for a little help with D3DXVECTOR2 pointers. Say I write a simple function that takes a D3DXVECTOR2 structure and fills it out, obviously the D3DXVECTOR2 parameter has to be passed in as a reference. Something like this... void ( D3DXVECTOR2 *position ) { *position.x = 320; *position.y = 240; } When I try and get this the compiler gives me an error. : error C2228: left of ''.x'' must have class/struct/union type : error C2228: left of ''.y'' must have class/struct/union type So what is the proper way to do this? Any help much appreciated, thanks.

IFooBar

May 3, 2003 at 1:25 PM

The "proper" way to do that would be to use brackets:-

(*position).x = 320;
(*position).y = 240;

And an even properer way would be to use the arrow operator becuase position is s pointer, so to access the members of a pointer you should use the ''->'' operator like so:

position->x = 320;
position->y = 240;

or you could just make life easier and make the function like this

void something( D3DXVECTOR& position )
{
position.x = 320;
position.y = 240;
}

that way the original variable gets altered instead of a copy and it''s cleaner then using all that pointer and dereferencing stuffage.

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Mr Teatime

May 4, 2003 at 9:55 AM

Ahh, I completely forgot about the arrow operator, oops.

Thanks for the help.

okonomiyaki

May 4, 2003 at 1:18 PM

quote:

or you could just make life easier and make the function like this

void something( D3DXVECTOR& position )
{
position.x = 320;
position.y = 240;
}

I''ve always wondered this. What exactly is happening here? I know that the ''&'' symbol represents a reference, but then aren''t you passing in a reference, and therefore position is a pointer? How can you use the ''.'' operator then?

Illumini

May 4, 2003 at 3:50 PM

Because the C++ refrence operator operates at two levels. Under the hood it is only passing an address. However to the programmer it is treated as simply an "alias" for the original variable.

[edited by - Illumini on May 4, 2003 6:29:35 PM]

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