C++ 如何使用对象的指针;构造函数和析构函数。C++;
我试图以特定的顺序创建和删除一个对象。默认情况下,首先使用构造函数-析构函数创建第一个对象,依此类推,析构函数从上次创建的对象开始删除。我正在尝试更改输出顺序,类似于以下内容:C++ 如何使用对象的指针;构造函数和析构函数。C++;,c++,object,constructor,destructor,C++,Object,Constructor,Destructor,我试图以特定的顺序创建和删除一个对象。默认情况下,首先使用构造函数-析构函数创建第一个对象,依此类推,析构函数从上次创建的对象开始删除。我正在尝试更改输出顺序,类似于以下内容: Object 1 is created, we've got 1 object(s) now! Object 2 is created, we've got 2 object(s) now! Object 3 is created, we've got 3 object(s) now! Object 3 is de
Object 1 is created, we've got 1 object(s) now!
Object 2 is created, we've got 2 object(s) now!
Object 3 is created, we've got 3 object(s) now!
Object 3 is deleted, we've got 2 object(s) now!
Object 2 is deleted, we've got 1 object(s) now!
Object 4 is created, we've got 2 object(s) now!
Object 4 is deleted, we've got 1 object(s) now!
Object 1 is deleted, we've got 0 object(s) now!
代码:
class Object {
public:
Object(int i) {
id = i;
count++;
cout<<"Object "<<id<<" is created, we've got "<<count<<" object(s) now!"<<endl;
}
~Object() {
count--;
cout<<"Object "<<id<<" is deleted, we've got "<<count<<" object(s) now!"<<endl;
}
private:
int id;
static int count;
};
到目前为止,它只创建了3个对象,并在创建后立即删除了第三个对象,我正在尝试在删除第三个对象之后删除第二个对象 您使用的
delete
无效,导致未定义的行为,因为您没有使用new
创建对象。如果您试图销毁堆栈上存在的对象,并且这些对象在超出范围时会自动销毁,则您无权手动销毁它们
如果要使用delete
控制销毁顺序,则必须使用new
,如下所示:
void TestObjects()
{
Object *obj1 = new Object(1);
Object *obj2 = new Object(2);
Object *obj3 = new Object(3);
delete obj3;
delete obj2;
Object *obj4 = new Object(4);
delete obj4;
delete obj1;
}
或者,在您的特定示例中,只需更多地控制对象的范围,而不使用new
和delete
即可获得相同的输出:
void TestObjects()
{
Object obj1(1);
{
Object obj2(2);
Object obj3(3);
} // <-- obj3 and obj2 are destroyed here, in that order!
Object obj4(4);
} // <-- obj4 and obj1 are destroyed here, in that order!
void TestObjects()
{
对象obj1(1);
{
对象obj2(2);
对象obj3(3);
}//你的程序表现出不明确的行为,并且可能会在许多C++实现中崩溃。你只能“代码>删除<代码> >你<代码>新< /代码> ED。没有例外的规则。是的,我忘了,谢谢。那么我如何控制对象的创建和删除?”斯坦利我在我的答案中覆盖了这个。再重新阅读一遍。小心
void TestObjects()
{
Object obj1(1);
{
Object obj2(2);
Object obj3(3);
} // <-- obj3 and obj2 are destroyed here, in that order!
Object obj4(4);
} // <-- obj4 and obj1 are destroyed here, in that order!