[Solved] Segmentation Fault... What can be?
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I try to use valgrind, but I got this error:
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** Error: "valgrind" could not be started: No such file or directory **
@I follow this page: "http://doc.qt.digia.com/qtcreator-2.5/creator-analyzer.html":http://doc.qt.digia.com/qtcreator-2.5/creator-analyzer.html
I will check if getEixo is null, but I don't beleave that's can be the reason of my problem...
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Header:
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#ifndef EIXO_H
#define EIXO_H#include <QObject>
#include "tipoeixo.h"
#include "sensor.h"class Eixo : public QObject
{
Q_OBJECT
public:
explicit Eixo(QObject *parent = 0);void setId(int newId); void setNumeroEixo(int newNumeroEixo); void setConjunto(int newConjunto); void setMyTipoEixo(TipoEixo* newMyTipoEixo); void setSensores(QList<Sensor*> newSensores); void addSensor(Sensor* newSensor); int getId(); int getNumeroEixo(); int getConjunto(); TipoEixo* getMyTipoEixo(); QList<Sensor*> getSensores(); bool isDiferencial();private:
int id;
int numeroEixo;
int conjunto;
TipoEixo* myTipoEixo;
QList<Sensor*> sensores;};
#endif // EIXO_H
@If I change sensores to be a pointer, like this: QList<Sensor*>* sensores;
The problem can be fixed?
I will try change this rightnow... -
[quote author="dcbasso" date="1348577357"]The value of variable getEixo() is <unavailable synchronous data>, on debug mode![/quote]
No debugger required. Stick a:
@QASSERT(getEixo())
// or
if (getEixo() == 0) qFatal("getEixo() is returning null");
@or similar check immediately before the affected line.
Incidentally, that affected line is adding an element to an anonymous copy of the QList<> and will probably not do what you are expecting.
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A debugger is not required, but way more useful for tracking issues like these.
But basically, this is your problem:
@getEixo()->getSensores().append( getSensorConfigurado() );@
Here, you do two dereferences. The first especially may be problematic. If there is any chance of getEixo() returning 0, then you need to check for that.@
Eixo* eixo = getEixo();
Q_ASSERT(eixo); //don't do the actual get inside the assert! It will be compiled out for release builds!
eixo->getSensores().append( getSensorConfigurado() );
@Note that even this does not get you out of the woods yet. You have to be sure that getEixo() always returns 0 or a valid pointer. If you have deleted the Eixo object earlier and the pointer is still returned here, you're in trouble that you can't catch like this.
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I found the reason!
I fix the error:
I was trying to append a some object/pointer to my QList! I remove the append, and just change the object/pointer and my QList is "auto" updated!I really don't undestand why the problem appears when we try to add same object/pointer to QList, but the error don't happened again!!!
Thanks all!
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If you don't understand, I really suggest you keep on it until you do. Otherwise, I almost guarantee you that you'll get bitten by the same issue again, only this time about an hour before your release deadline...
The way you talk about object/pointer gives me the feeling you don't quite understand pointers & objects yet. However, that knowledge really is needed in order to work effectively with C++ and Qt.
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I just use the thermology "object/pointer" to suggest that I was working with pointer to change a object, as this:
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QList<Sensor*> sensores;
@Well, I search a lot about this error and I don't found any good explanation to the error. After I remove the ".append(Sensor*)" on object sensores, the problem was fix, and the "Sensor*" is changed anyway, because I use pointer to change the value os "Sensor" inside the QList!
I just make the mistake to try add again on the QList... I think...