没有调用析构函数?
Destructors not called?
我正在尝试跟踪此程序,但由于某种原因它显示
进程以退出代码 4 结束。
并在不调用析构函数的情况下结束?可能是什么原因?
#include <iostream>
using namespace std;
class A {
public:
A() { cout << "A ctor" << endl; }
A(const A& a) { cout << "A copy ctor" << endl; }
virtual ~A() { cout << "A dtor" << endl; }
virtual void foo() { cout << "A foo()" << endl; }
virtual A& operator=(const A& rhs) { cout << "A op=" << endl; }
};
class B : public A {
public:
B() { cout << "B ctor" << endl; }
virtual ~B() { cout << "B dtor" << endl; }
virtual void foo() { cout << "B foo()" << endl; }
protected:
A mInstanceOfA; // don't forget about me!
};
A foo(A& input)
{
input.foo();
return input;
}
int main()
{
B myB;
B myOtherB;
A myA;
myOtherB = myB;
myA = foo(myOtherB);
}
您的程序表现出未定义的行为,即到达 non-void 函数的右大括号(此处为 operator=
)而没有遇到 return
语句。
对我来说(使用 gcc 8.3.0)效果很好。但我收到警告:
test.cpp: In member function ‘virtual A& A::operator=(const A&)’:
test.cpp:10:63: warning: no return statement in function returning non-void [-Wreturn-type]
virtual A& operator=(const A& rhs) { cout << "A op=" << endl; }
然后打印出来:
A ctor
A ctor
B ctor
A ctor
A ctor
B ctor
A ctor
A op=
A op=
B foo()
A copy ctor
A op=
A dtor
A dtor
B dtor
A dtor
A dtor
B dtor
A dtor
A dtor
也许你应该尝试解决这个警告。
我正在尝试跟踪此程序,但由于某种原因它显示 进程以退出代码 4 结束。 并在不调用析构函数的情况下结束?可能是什么原因?
#include <iostream>
using namespace std;
class A {
public:
A() { cout << "A ctor" << endl; }
A(const A& a) { cout << "A copy ctor" << endl; }
virtual ~A() { cout << "A dtor" << endl; }
virtual void foo() { cout << "A foo()" << endl; }
virtual A& operator=(const A& rhs) { cout << "A op=" << endl; }
};
class B : public A {
public:
B() { cout << "B ctor" << endl; }
virtual ~B() { cout << "B dtor" << endl; }
virtual void foo() { cout << "B foo()" << endl; }
protected:
A mInstanceOfA; // don't forget about me!
};
A foo(A& input)
{
input.foo();
return input;
}
int main()
{
B myB;
B myOtherB;
A myA;
myOtherB = myB;
myA = foo(myOtherB);
}
您的程序表现出未定义的行为,即到达 non-void 函数的右大括号(此处为 operator=
)而没有遇到 return
语句。
对我来说(使用 gcc 8.3.0)效果很好。但我收到警告:
test.cpp: In member function ‘virtual A& A::operator=(const A&)’:
test.cpp:10:63: warning: no return statement in function returning non-void [-Wreturn-type]
virtual A& operator=(const A& rhs) { cout << "A op=" << endl; }
然后打印出来:
A ctor
A ctor
B ctor
A ctor
A ctor
B ctor
A ctor
A op=
A op=
B foo()
A copy ctor
A op=
A dtor
A dtor
B dtor
A dtor
A dtor
B dtor
A dtor
A dtor
也许你应该尝试解决这个警告。