Pointers question

I am trying to write use pointers for some function arguments. The reason I am using pointers and not references is that either the src or dst arguments might be NULL.

Code:

---

Vec3 TFormPoint(const Vec3& point, Entity* src, Entity* dst)
{
        Mat4* srcmat;
        Mat4* dstmat;
        if (src!=0) {
                srcmat = src.mat;
        }
        if (dst!=0) {
                dstmat = dst.mat;
        }
        //do some more stuff
}

---

The entity class looks like this:

Code:

---

class Entity
{
        public:
        Entity();
        Mat4 mat;
}

---

Why is the compiler complaining that "left of '.mat' must have class/struct/union"? How do I convert the reference to a pointer? What should this code look like?

Because src and dst are pointers, as you have written. Thus what you are looking to do is:

Code:

---

srcmat = src->mat;
dstmat = dst->mat;

---

Looks like now it needs to convert the mat reference to a pointer?:

Code:

---

Vec3 TFormPoint(const Vec3& point, Entity* src, Entity* dst)
{
        Mat4* srcmat;
        Mat4* dstmat;
        if (src!=0) {
                srcmat = src->mat;
        }
        if (dst!=0) {
                dstmat = dst->mat;
        }
        //Do stuff
}

---

Quote:

---

1>c:\projects\leadwerks 3.0\engine\transform.cpp(21) : error C2440: '=' : cannot convert from 'DE2::Mat4' to 'DE2::Mat4 *'

---

Error occurs on this line:

Code:

---

srcmat = src->mat;

---

Well I was just guessing since you did not post the code to the Entity class; if mat is not a pointer then:

Code:

---


srcmat = &(*src).mat;

---

Thanks, it seems to be working.

Or simply:

Code:

---

srcmat = &src->mat;

---

Be careful with the case where it is null though. At the moment srcmat will simply be uninitialised!

Yep:

Code:

---

if (src!=NULL)
{
srcmat = &src->mat;
}

---

I ended up making a few overloaded functions so that both references and pointers can be used. References would be adequate if they could be set to null, but they can't.