The memory cound not be "read". - random crash
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开发者_StackOverflow社区.
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(..)
.
try using :
CSceneNode* pRoot = nodes.at(0);
If you get an exception, then you know something is wrong. Maybe your filter is too restrictive or you don't have child so nothing is returned.
You shouldn't use nodes[i]
if you aren't 100% sure that the i
index is valid.
What you want to do is make sure the vector isn't empty:
CSceneNode *const pRoot = nodes.empty() ? NULL : nodes[0];
if (pRoot != NULL)
{
// Do something...
}
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