Why should this code snippet crash?

[lucky6969b]

I've got memory leak on the delete line when being commented out
On the other hand, I've got a crash. Where is the bug?
The reason I use a float* because some function requires me this type of parameter to pass in.
I can't convert a float[][] to a float*
Thanks
Jack

struct NavPath
{
	NavPath() {
		positions = new float[MAX_PATH_NODES*3];
		count = 0;
	}

	~NavPath() {
		if (positions) {
			delete[] positions;
			positions = 0;
		}

	}	 
    float *positions;
    std::size_t count;
};

[superbonzo]

Where is the bug?

not there, your bug is somewhere else.
BTW,

~NavPath() {
if (positions) {
delete[] positions;
positions = 0;
}

avoid this kind of defensive style, it's useless at best ( you can safely delete a null pointer ), and it may hide existing bugs ... ( what if the pointer is erroneously set to null somewhere before the destructor gets called ? you won't know ... )

[lucky6969b]

It simply crashes here after the return statement

std::vector<D3DXVECTOR3> ConvertNavPathToVector3(NavPath* navPath) {
	std::vector<D3DXVECTOR3> vector3;

	for (int i = 0; i < navPath->count; i++) {
		D3DXVECTOR3 vec3;
		vec3.x = *navPath->positions++;
		vec3.y = *navPath->positions++;
		vec3.z = *navPath->positions++;
		vector3.push_back(vec3);
	}

	return vector3;
}

bool NavMesher::findPath(const D3DXVECTOR3& from, const D3DXVECTOR3& to, std::vector<D3DXVECTOR3>& resultPath)
{
        if(nullptr == m_navQuery)
        {
                return false;
        }
        if(nullptr == m_navMesh)
        {
                return  false;
        }
     
        dtQueryFilter queryFilter;
        dtPolyRef startRef;
        dtPolyRef endRef;
     
        dtPolyRef returnedPath[MAX_PATH_NODES];
        float extents[3];
        extents[0] = 2.f;
        extents[1] = 4.f;
        extents[2] = 2.f;
     
     
        m_navQuery->findNearestPoly(from, extents, &queryFilter, &startRef, 0);
        if (startRef == 0)
        {
                return false;
     
        }
        m_navQuery->findNearestPoly(to, extents, &queryFilter, &endRef, 0);
        if (endRef == 0)
        {
                return false;
     
        }
        dtStatus findStatus = DT_FAILURE;
        int pathCount;
     
        findStatus = m_navQuery->findPath(startRef, endRef, from, to, &queryFilter, returnedPath, &pathCount, MAX_PATH_NODES);
        if (dtStatusFailed(findStatus))
        {
                return false;
        }
     
        if(pathCount > 0)
        {
                int numNodes = 0;
		NavPath path;
		// find an array of vectors within a path corridor
		findStatus = m_navQuery->findStraightPath(from, to, returnedPath, pathCount, path.positions, 0, 0, &numNodes, MAX_PATH_NODES);
		if(dtStatusFailed(findStatus))
                {
                        return false;
                }
		path.count = numNodes;
		resultPath = ConvertNavPathToVector3(&path);   
				
		return true;
		 
        }
        return true;
}

The path.positions parameter is basically passed in as a pointer of floats
Thanks
Jack

[superbonzo]

you're incrementing the positions member that in turn is delete'd later, causing UB and hence the crash. This would not have happened if the NavPath class and the ConvertNavPathToVector3 function were const-correct ! at worst, it should be something like:

std::vector<D3DXVECTOR3> ConvertNavPathToVector3( NavPath const& navPath ) {
	std::vector<D3DXVECTOR3> vector3;
	float const* positions = navPath.positions;

	for (int i = 0; i < navPath->count; i++) {
		D3DXVECTOR3 vec3;
		vec3.x = *positions++;
		vec3.y = *positions++;
		vec3.z = *positions++;
		vector3.push_back(vec3);
	}

	return vector3;
}

[lucky6969b]

Thanks, it's working okay now.
Jack