【1】qDeleteAll应用示例
qDeleteAll源码如下：
template <typename ForwardIterator>
Q_OUTOFLINE_TEMPLATE void qDeleteAll(ForwardIterator begin, ForwardIterator end)
{
while (begin != end)
{
delete *begin;
++begin;
}
} template <typename Container>
inline void qDeleteAll(const Container &c)
{
qDeleteAll(c.begin(), c.end());
}
示例代码如下：
#include <QMap>
#include <QString>
#include <QWidget>
#include <QDebug>
#include <QApplication> class PersonInfo
{
public:
PersonInfo(int id = -, QString name = QString(), QWidget* pWidget = NULL)
: m_nId(id)
, m_name(name)
, m_pWidget(pWidget)
{} ~PersonInfo()
{
m_nId = -;
m_name = QString();
if (m_pWidget != NULL)
{
qDebug() << "delete personInfo :: " << this;
delete m_pWidget;
m_pWidget = NULL;
}
}
private:
int m_nId;
QString m_name;
QWidget* m_pWidget;
}; int main(int argc, char *argv[])
{
QApplication a(argc, argv); QMap<int, PersonInfo *> map;
for (int i = ; i < ; ++i)
{
PersonInfo *pTemp = new PersonInfo(i + , QString("hello World!"), (new QWidget()));
qDebug() << "construct personInf :: " << pTemp;
map.insert(i, pTemp);
} qDeleteAll(map); // 1.释放内存
qDebug() << "after qDeleteAll size :: " << map.size() << endl;
map.clear(); // 2.必须清空
qDeleteAll(map); // 3.再次释放内存 return a.exec();
}
打印结果如下：
construct personInf :: 0x3bdc20
construct personInf :: 0x3c0308
construct personInf :: 0x3bfe08
construct personInf :: 0x3c0a88
construct personInf :: 0x3c1248
construct personInf :: 0x3c1738
construct personInf :: 0x3c1bb8
construct personInf :: 0x3c2420
construct personInf :: 0x3c26d0
construct personInf :: 0x3c2c68
delete personInfo :: 0x3bdc20
delete personInfo :: 0x3c0308
delete personInfo :: 0x3bfe08
delete personInfo :: 0x3c0a88
delete personInfo :: 0x3c1248
delete personInfo :: 0x3c1738
delete personInfo :: 0x3c1bb8
delete personInfo :: 0x3c2420
delete personInfo :: 0x3c26d0
delete personInfo :: 0x3c2c68
after qDeleteAll size ::
尤其注意打印结果。
可以尝试把2.清空容器行注释掉，然后再运行程序，查看运行结果。
【2】总结
qDeleteAll只负责释放容器元素内存，但没有对容器的置空操作。若无意间二次再执行qDeleteAll过程，程序必会崩溃。
为了避免可恶的崩溃，切记qDeleteAll之后必须清空容器。
Good Good Study, Day Day Up.
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