Question

I’m having a static linking problem in my C++ app. I’m hoping you can help. Code for header and source below.

#ifndef PRACTICARDSDB_H
#define PRACTICARDSDB_H
#include "cardset.h"
#include "card.h"
#include "filter.h"

class PractiCardsDB
{
public:
    PractiCardsDB();
    static void resetAll();
    static void resetDates();
    static CardSet getCardSet();
    static CardSet getCardSet(Filter filter);
    static void addCard(Card card);
    static void editCard(Card card);
    static void deleteCard(Card card);
    static bool createConnection();

};

#endif // PRACTICARDSDB_H

Above is the header file and below is the source file.

#include "practicardsdb.h"
#include <QtSql/QSqlDatabase>
#include <QMessageBox>

PractiCardsDB::PractiCardsDB() {}
static bool PractiCardsDB::createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("EnglishSpanish");
    if (!db.open())
    {
        return false;
    }
    return true;
}

The error I receive is: cannot declare member function ‘static bool PractiCardsDB::createConnection()’ to have static linkage. Any help?

I’m using Qt 4.7 with C++ inside Qt Creator if it helps.

Answer 1

When you define a static member function separately from the declaration, you do not have to use the static modifier.

bool PractiCardsDB::createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("EnglishSpanish");
    if (!db.open())
    {
        return false;
    }
    return true;
}

Also do you really mean to make every single function of your class static? Your class represents a database of sorts for Card objects, so I think you’d want to actually store member data with the class itself?

Even in that snippet above, you create a QSqlDatabase object, but db‘s existence is only the extent of the createConnection() function.