关于复制构造函数和赋值操作符的问题

[degree_37]

自己写的程序中不停的出现两个问题:
1>.\face3d.cpp(8) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const QVector3d' (or there is no acceptable conversion)
1> f:\corn\qreadobj\vector3d.h(38): could be 'QVector3d QVector3d::operator =(QVector3d &)'
1> while trying to match the argument list '(QVector3d, const QVector3d)'
1>scene3d.cpp
1>d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(481) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const QFace3d' (or there is no acceptable conversion)
1> f:\corn\qreadobj\face3d.h(21): could be 'QFace3d QFace3d::operator =(QFace3d &)'
1> while trying to match the argument list '(QFace3d, const QFace3d)'
1> d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(473) : while compiling class template member function 'void QVector<T>::append(const T &)'
1> with
1> [
1> T=QFace3d
1> ]
1> f:\corn\qreadobj\group3d.h(13) : see reference to class template instantiation 'QVector<T>' being compiled
1> with
1> [
1> T=QFace3d
1> ]
1>d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(474) : error C2558: class 'QVertex3d' : no copy constructor available or copy constructor is declared 'explicit'
1> d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(473) : while compiling class template member function 'void QVector<T>::append(const T &)'
1> with
1> [
1> T=QVertex3d
1> ]
1> f:\corn\qreadobj\scene3d.h(16) : see reference to class template instantiation 'QVector<T>' being compiled
1> with
1> [
1> T=QVertex3d
1> ]
1>d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(479) : error C2558: class 'QVertex3d' : no copy constructor available or copy constructor is declared 'explicit'
1>d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(474) : error C2558: class 'QVector3d' : no copy constructor available or copy constructor is declared 'explicit'
1> d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(473) : while compiling class template member function 'void QVector<T>::append(const T &)'
1> with
1> [
1> T=QNormal
1> ]
1> f:\corn\qreadobj\scene3d.h(17) : see reference to class template instantiation 'QVector<T>' being compiled
1> with
1> [
1> T=QNormal
1> ]
1>d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(479) : error C2558: class 'QVector3d' : no copy constructor available or copy constructor is declared 'explicit'
1>d:\qt\include\qtcore\../../src/corelib/tools/qvector.h(481) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const QNormal' (or there is no acceptable conversion)
1> f:\corn\qreadobj\vector3d.h(38): could be 'QVector3d QVector3d::operator =(QVector3d &)'
1> while trying to match the argument list '(QNormal, const QNormal)'

但是error中提示的复制构造函数和赋值操作符我明明已经在程序中定义了啊,怎么就是说没定义呢... 如下:

QVector3d QVector3d::operator =(QVector3d &vector3d)
{
	m_x = vector3d.m_x;
	m_y = vector3d.m_y;
	m_z = vector3d.m_z;
	return *this;
}
QFace3d QFace3d::operator =(QFace3d &face)
{
	v0 = face.v0;
	v1 = face.v1;
	v2 = face.v2;
	m_Normal = face.m_Normal;
}

请高手指点~

[Dinelgua]

注意发生问题的是'const QVector3d'
是const类型 不能修改内容

如果是普通类型QVector3d 是没有问题的 俺测试过了

[Dinelgua]

class ''QVector3d' ' : no copy constructor available or copy constructor is declared

这是缺少拷贝构造函数
楼住加一个就行
QVector3d(const QVector3d&)


error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const QNormal'
此错误同迁移贴内答复 是const导致的，非const没有问题可以使用operator=

[hhyttppd]

QVector3d operator =(QVector3d const &vector3d);

QVector3d(QVector3d const &);

[degree_37]

回1楼： 我去掉了const 还是有同样的错误 而且错误多了两个， 应该不是const的问题 构造函数中没有修改东西的~~

[waizqfor]

QVector3d QVector3d::operator =(QVector3d const &vector3d)
{
    m_x = vector3d.m_x;
    m_y = vector3d.m_y;
    m_z = vector3d.m_z;
    return *this;
}
QFace3d QFace3d::operator =(QFace3d const &face)
{
    v0 = face.v0;
    v1 = face.v1;
    v2 = face.v2;
    m_Normal = face.m_Normal;
}

试试

[degree_37]

根据三楼的方法，已经解决了！ 但是不知道原因...

为什么我写成

QVertex3d::QVertex3d(QVertex3d &vertex3d)

就不行呢

写成

QVertex3d(QVertex3d const &);

就可以...

[Dinelgua]

因为你操作的是const对象

[Dinelgua]

[Quote=引用 4 楼 degree_37 的回复:]
回1楼： 我去掉了const 还是有同样的错误 而且错误多了两个， 应该不是const的问题 构造函数中没有修改东西的~~
[/Quote]

下面是我测试代码，A a1,a2; 时编译通过， const A a1,a2;时报于楼住相同错误

class A
{
public:
	A():i(10)
	{

	};
	A operator =(A& a)
	{
		this->i = a.i;
		return *this;
	};
private:
	int i;
};
//typedef int* iPTYPE;
void main(void) 
{ 
    A a1,a2;
	a1 = a2;
}