c++ my program breaks with weird error - c++

Question

when i run my program it compiles fine but when it runs i get this box which stops my program. the box says this Unhandled exception at 0x0039e9a7 in Mon.exe: 0xC0000005: Access violation reading location 0xcdcdcdcd. i don't even know what that means. when it breaks it point at this function.
void CXFileEntity::SetAnimationSet(unsigned int index)
{
if (index==m_currentAnimationSet)
return;
if (index>=m_numAnimationSets)
index=0;
// Remember current animation
m_currentAnimationSet=index;
// Get the animation set from the controller
LPD3DXANIMATIONSET set;
IT BREAKS HERE>>>>m_animController->GetAnimationSet(m_currentAnimationSet, &set );
// Note: for a smooth transition between animation sets we can use two tracks and assign the new set to the track
// not currently playing then insert Keys into the KeyTrack to do the transition between the tracks
// tracks can be mixed together so we can gradually change into the new animation
// Alternate tracks
DWORD newTrack = ( m_currentTrack == 0 ? 1 : 0 );
// Assign to our track
m_animController->SetTrackAnimationSet( newTrack, set );
set->Release();
// Clear any track events currently assigned to our two tracks
m_animController->UnkeyAllTrackEvents( m_currentTrack );
m_animController->UnkeyAllTrackEvents( newTrack );
// Add an event key to disable the currently playing track kMoveTransitionTime seconds in the future
m_animController->KeyTrackEnable( m_currentTrack, FALSE, m_currentTime + kMoveTransitionTime );
// Add an event key to change the speed right away so the animation completes in kMoveTransitionTime seconds
m_animController->KeyTrackSpeed( m_currentTrack, 0.0f, m_currentTime, kMoveTransitionTime, D3DXTRANSITION_LINEAR );
// Add an event to change the weighting of the current track (the effect it has blended with the secon track)
m_animController->KeyTrackWeight( m_currentTrack, 0.0f, m_currentTime, kMoveTransitionTime, D3DXTRANSITION_LINEAR );
// Enable the new track
m_animController->SetTrackEnable( newTrack, TRUE );
// Add an event key to set the speed of the track
m_animController->KeyTrackSpeed( newTrack, 1.0f, m_currentTime, kMoveTransitionTime, D3DXTRANSITION_LINEAR );
// Add an event to change the weighting of the current track (the effect it has blended with the first track)
// As you can see this will go from 0 effect to total effect(1.0f) in kMoveTransitionTime seconds and the first track goes from
// total to 0.0f in the same time.
m_animController->KeyTrackWeight( newTrack, 1.0f, m_currentTime, kMoveTransitionTime, D3DXTRANSITION_LINEAR );
// Remember current track
m_currentTrack = newTrack;
}
any idea?
UPDATE
this is the class
class CXFileEntity
{
private:
LPDIRECT3DDEVICE9 m_d3dDevice; // note: a pointer copy (not a good idea but for simplicities sake)
// Direct3D objects required for animation
LPD3DXFRAME m_frameRoot;
LPD3DXANIMATIONCONTROLLER m_animController;
D3DXMESHCONTAINER_EXTENDED* m_firstMesh;
// Bone data
D3DXMATRIX *m_boneMatrices;
UINT m_maxBones;
// Animation variables
unsigned int m_currentAnimationSet;
unsigned int m_numAnimationSets;
unsigned int m_currentTrack;
float m_currentTime;
float m_speedAdjust;
// Bounding sphere (for camera placement)
D3DXVECTOR3 m_sphereCentre;
float m_sphereRadius;
std::string m_filename;
void UpdateFrameMatrices(const D3DXFRAME *frameBase, const D3DXMATRIX *parentMatrix);
void UpdateSkinnedMesh(const D3DXFRAME *frameBase);
void DrawFrame(LPD3DXFRAME frame) const;
void DrawMeshContainer(LPD3DXMESHCONTAINER meshContainerBase, LPD3DXFRAME frameBase) const;
void SetupBoneMatrices(D3DXFRAME_EXTENDED *pFrame/*, LPD3DXMATRIX pParentMatrix*/);
public:
CXFileEntity(LPDIRECT3DDEVICE9 d3dDevice);
~CXFileEntity(void);
bool Load(const std::string &filename);
void FrameMove(float elapsedTime,const D3DXMATRIX *matWorld);
void Render() const;
void SetAnimationSet(unsigned int index);
void NextAnimation();
void AnimateFaster();
void AnimateSlower();
D3DXVECTOR3 GetInitialCameraPosition() const;
unsigned int GetCurrentAnimationSet() const {return m_currentAnimationSet;}
std::string GetAnimationSetName(unsigned int index);
std::string GetFilename() const {return m_filename;}
};
im releasing m_animController in the destructor

Answer 1

0xC0000005: Access violation reading
location 0xcdcdcdcd.
Well it's simple :
Access violation is an error where you tried to access some memory that are allowed to be accessed. For example you might be trying to use a null pointer.
Here the 0xcdcdcdcd part is a special adress put by visual studio when a pointer have been deleted (or more precisely, the object pointed by the pointer is destroyed and the pointer is set to this value) or non-initialized > (edit: I'm not sure anymore, will have to check the VS documentation). That's true only in Debug mode if my memory is correct.
So here, m_animController is in a wrong state (as it seems that it's the unique pointer of the expression where it crashes).
First, I would suggest that you make sure that delete have not been called before on this pointer. It might be obvious or it might be that you call delete in the object destructor and you didn't see that this object have bee destroyed or copied. If your object (CXFileEntity) must not be copied, make sure it can't be (by inheriting from boost::noncopiable or by putting it's copy constructor and copy operator in private with no implementation).
Next, if you really have to use raw pointers (instead of references or smart pointers) you'd better check all your pointers (and other contextual values) at the start of each function, using assertions (look for assertions in google and stackoverflow, there is a lot of discussions about that). Even better: check that pointers are valid each time you get them from functions. That will help you track early when a a pointer got in a state you didn't expect.

Answer 2

You attempted to access memory to which you do not have access. Most commonly this is because you are using a pointer that you have not initialized and it points to an address that's not in your process's memory space.
You should make sure that m_animController is initialized (and pointing to a valid object) before you dereference it with the -> operator.

Answer 3

You have a bad pointer somewhere. Based on the line where it breaks, I'm guessing m_animController has a bad value. Check that m_animController is initialized to a default value. And make sure you aren't deleting it somewhere before using it.
Note: 0xcdcdcdcd is a common value that some debuggers will initialize invalid pointers with, but it's not guaranteed.