Question

I have a problem with a random crash caused by CSceneNode* pRoot = nodes[0]; // The real problem is = nodes[0];
Crash message is: The instruction at “0x0059d383” referenced memory at “0x00000000”. The memory cound not be “read”.
I do not see the problem, could please help me out ?

In Save.cpp

void CNESave::SaveLocation(CNELocation* pLoc)
// Other code

    CSceneNode* scene = pLoc->GetScene();
    vector<CSceneNode*> nodes;          
    scene->GetNodes(GetNodesByPartOfName, nodes, &string("_Ldynamic"));
    CSceneNode* pRoot = nodes[0];   //This is the problem causing random crashes!
        // If I change it (just for testing) to CSceneNode* pRoot = scene 
        // them it isn't crashing.
        // So CSceneNode* pRoot is OK and the problematic part is = nodes[0];

In SceneNode.cpp

bool GetNodesByPartOfName(CSceneNode* node, const void *data)
{
    string *str = (string *)data;
    return node->GetName().find(*str)!=npos;
}

void CSceneNode::GetNodes( GetNodesFunc gf, vector<CSceneNode*> &nodes, 
   const void *data)
{
    if (gf(this, data)) nodes.push_back(this);
    SceneNodeIterator begin=FirstChild(), end=LastChild();
    for (;begin!=end;begin++) ((CSceneNode*)*begin)->GetNodes(gf, nodes, data);
}

CSceneNode* CSceneNode::CreateNew() 
{
    return new CSceneNode();
}

// a lot of other code

In SceneNode.h

class EXPORTDECL CSceneNode;
typedef bool (*GetNodesFunc)(CSceneNode *node, const void *data);
EXPORTDECL bool GetNodesByPartOfName(CSceneNode* node, const void *data);
typedef vector<CSceneNode*>::iterator SceneNodeIterator;
class EXPORTDECL CSceneNode : public CTreeNode<CSceneNode, true>  
{
public:
//construction & destruction
    CSceneNode();
    virtual ~CSceneNode();
    virtual CSceneNode *CreateNew();
// a lot of other code

---

Solved. Thank you guys very much.

Answer 1

If the result of node->GetName() does not contain the string _Ldynamic, this will crash.

Because in this case GetNodesByPartOfName(..) will return false and GetNodes(..) will not execute nodes.push_back(this) and you will be left with an empty vector and later will try to access the first element of this empty vector after returning from GetNodes(..).