Qt对象之间可以存在父子关系
-每一个对象都保存有它所有子对象的指针
-每一个对象都有一个指向其父对象的指针
parent是一个对象，它里面有一个子对象指针链表，里面的每个指针指向了一个子对象。这些子对象也存有指向parent的指针
Qt中的对象如何指定它的父对象呢？
当指定Qt对象的父对象时
-其父对象会在子对象链表中加入该对象的指针
-该对象会保存指向其父对象的指针
QObject* p = new QObject();
QObject* c1 = new QObject();
QObject* c2 = new QObject();
c1->setParent(p); //执行该条语句时，其父对象会在子对象链表中加入该对象的指针；该对象会保存指向其父对象的指针
c2->setParent(p);
对象间的父子关系
#include <QApplication>
#include <QDebug>
void fcTest()
{
QObject* p = new QObject();
QObject* c1 = new QObject();
QObject* c2 = new QObject();
c1->setParent(p);
c2->setParent(p);
qDebug() << "c1:" << c1;
qDebug() << "c2:" << c2;
const QObjectList& list = p->children();
for(int i=0; i<list.length(); i++)
{
qDebug() << list[i] ;
}
qDebug() << "p:" << p;
qDebug() << "c1 parent" << c1->parent();
qDebug() << "c2 parent" << c2->parent();
}
int main(int argc, char* argv[])
{
QApplication a(argc,argv);
fcTest();
return a.exec();
}
c1: QObject(0x61d7b8)
c2: QObject(0x61d7c8)
QObject(0x61d7b8)
QObject(0x61d7c8)
p: QObject(0x61d7a8)
c1 parent QObject(0x61d7a8)
c2 parent QObject(0x61d7a8)
当Qt对象销毁时
-将自己从父对象的Children List移除
-将自己的Children List中的所有对象销毁
使用Qt开发时，不仅要时刻注意内存泄露的问题，还要时刻关注对象是否可能被多次销毁的问题
利用利用Qt对象间的父子关系可以构成对象树
删除树中的节点时会导致对应的子树被销毁
#include <QApplication>
#include <QDebug>
class MObj : public QObject
{
QString m_name;
public:
MObj(const QString& name)
{
m_name = name;
qDebug() << "Construct" << m_name;
}
~MObj()
{
qDebug() << "Destructor" << m_name;
}
};
void delTest()
{
MObj* obj1 = new MObj("obj1");
MObj* obj2 = new MObj("obj2");
MObj* obj3 = new MObj("obj3");
MObj* obj4 = new MObj("obj4");
obj2->setParent(obj1);
obj3->setParent(obj1);
obj4->setParent(obj3);
delete obj3;
const QObjectList& list = obj1->children();
qDebug() << "obj2:" << obj2;
for(int i=0; i<list.length(); i++)
{
qDebug() << list[i] ;
}
}
int main(int argc, char* argv[])
{
QApplication a(argc,argv);
delTest();
return a.exec();
}
c1: QObject(0x4bd7b8)
c2: QObject(0x4bd7c8)
QObject(0x4bd7b8)
QObject(0x4bd7c8)
p: QObject(0x4bd7a8)
c1 parent QObject(0x4bd7a8)
c2 parent QObject(0x4bd7a8)
Construct "obj1"
Construct "obj2"
Construct "obj3"
Construct "obj4"
Destructor "obj3"
Destructor "obj4"
obj2: QObject(0x4bc9b0)
QObject(0x4bc9b0)
原文：https://www.cnblogs.com/-glb/p/12320229.html