Despair

[mikro]

help please! i am getting crashes at a trivial point where there should be no crashes and i can't understand why. I am afraid this is going to be rather long, simply because i will have to quote some stuff, probably you can read this from bottom (where i include a trace) to top.

i have one class cMassnahme, which is a subclass of QListWidgetItem and is initiated as a singleton.

the cMassnahme-objects are created by my mainwindow (MainWindow). There can be more than one cMassnahme object with different ids which seems to work.

(listMassnahmen is a QListWidgetItem which will be parent )

void MainWindow::fillMassnahmen() {
    QString sql="SELECT idMassnahme,bezeichnung FROM pMassnahmen";
    QSqlQuery query(sql,db);
    massnahmen.clear();
 
    cbMassnahme->insertItem(0,"--- please choose ---");
    int row = 1;
    while (query.next()) {
        QString id  = query.value(0).toString();
        QString bez = query.value(1).toString();
        cMassnahme* currMass = cMassnahme::self(id,listMassnahmen);
 
	// Fill a Combobox as well
        cbMassnahme->insertItem(row,currMass->getBezeichnung());
 
        // some QMaps to make sure i find my stuff again
        massnahmen[id]       = currMass;
        massnahmenIDs[id]    = row;
        massnahmeFromID[row] = currMass;
 
        row++;
    }
 }

void MainWindow::fillMassnahmen() {
    QString sql="SELECT idMassnahme,bezeichnung FROM pMassnahmen";
    QSqlQuery query(sql,db);
    massnahmen.clear();

    cbMassnahme->insertItem(0,"--- please choose ---");
    int row = 1;
    while (query.next()) {
        QString id  = query.value(0).toString();
        QString bez = query.value(1).toString();
        cMassnahme* currMass = cMassnahme::self(id,listMassnahmen);

	// Fill a Combobox as well
        cbMassnahme->insertItem(row,currMass->getBezeichnung());

        // some QMaps to make sure i find my stuff again
        massnahmen[id]       = currMass;
        massnahmenIDs[id]    = row;
        massnahmeFromID[row] = currMass;

        row++;
    }
 }

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later on i open a new window of the class ConfigWindow from MainWindow. I need a combobox that will allow me to choose between the massnahmen in this Window as well. to create this i have a very simple function:

void ConfigWindow::fillMassnahmen() {
	cbMassnahmen->insertItems(0,mw->getMassnahmenContent());
}

void ConfigWindow::fillMassnahmen() {
	cbMassnahmen->insertItems(0,mw->getMassnahmenContent());
}

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which should work, as mw is a pointer to the mainwindow-class. and the getMassnahmenContent() looks like this:

QStringList MainWindow::getMassnahmenContent() {
	QStringList list;
	int allM = cbMassnahme->count();
	for (int i=0;i<allM;i++) {
		list.insert(i,cbMassnahme->itemText(i));
	}
	return list;
}

QStringList MainWindow::getMassnahmenContent() {
	QStringList list;
	int allM = cbMassnahme->count();
	for (int i=0;i<allM;i++) {
		list.insert(i,cbMassnahme->itemText(i));
	}
	return list;
}

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up to this point everything seems to work. now while the combobox in ConfigWindow is filled this slot is called:

void ConfigWindow::on_cbMassnahmen_currentIndexChanged ( int index) {
    QLocale loc;
 
    currentMassnahme = mw->getMassnahmeFromRow(index);
    QString bez            = currentMassnahme->getBezeichnung();
    ...

void ConfigWindow::on_cbMassnahmen_currentIndexChanged ( int index) {
    QLocale loc;

    currentMassnahme = mw->getMassnahmeFromRow(index);
    QString bez            = currentMassnahme->getBezeichnung();
    ...

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the two functions here are rather simple as well. mw is a pointer back to the MainWindow, with the function

cMassnahme* MainWindow::getMassnahmeFromRow(int row) {
    return massnahmeFromID[row];
}

cMassnahme* MainWindow::getMassnahmeFromRow(int row) {
    return massnahmeFromID[row];
}

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and the second line refering to this function:

QString cMassnahme::getBezeichnung() {
	return bezeichnung;
}

QString cMassnahme::getBezeichnung() {
	return bezeichnung;
}

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now, finally, the funny part: the application crashes in the last function! DrMingw gives me this trace:

Call stack:
004D3C48 werter.exe:004D3C48 QString::QString(QString const&) qstring.h:608
...
{ if (!isNull()) *this = QString(); }
inline QString::QString(const QString &s) : d(s.d)
> { Q_ASSERT(&s != this); d->ref.ref(); }
inline int QString::capacity() const
{ return d->alloc; }
...

0043B0CC werter.exe:0043B0CC cMassnahme::getBezeichnung() massnahme.cpp:82
...
QString cMassnahme::getBezeichnung() {
return bezeichnung;
> }

float cMassnahme::getKostenNettoSumme() {
...

0045B0AB werter.exe:0045B0AB ConfigWindow:n_cbMassnahmen_currentIndexChanged(int) ConfigWindow.cpp:259
...

currentMassnahme = mw->getMassnahmeFromRow(index);
> QString bez = currentMassnahme->getBezeichnung();

leBezeichnung->setText(bez);
...

any idea what should bother the application at this point?

[jacek]

void ConfigWindow::on_cbMassnahmen_currentIndexChanged ( int index) {
...
currentMassnahme = mw->getMassnahmeFromRow(index);
QString bez = currentMassnahme->getBezeichnung();
...

What is the value of "index" when your program crashes? How many items there are in massnahmeFromID? How do you initialize it?

[mikro]

aarghss. it was so easy and once again i spend hours being blind. of course there is no reason for the program to crash where it did: the combobox will have "---please choose ---" as a first item, so index can be 0 but of course the QMap only has entries for rows that have a massnahme.
Thank you for your quick reply which got me to finally look at the right place.