new in constructor for class 'Name' which has no assignment operator -- Within a
constructor for the cited class, there appeared a new. However, no assignment operator was
declared for this class. Presumably some class member (or members) points to dynamically
allocated memory. Such memory is not treated properly by the default assignment operator.
Normally a custom assignment operator would be needed. Thus, if x and y are both of type
Symbol
x = y;
will result in pointer duplication. A later delete would create chaos.
这个错误出现的原因就是在一个类的成员变量中,出现动态申请内存的情况(即这个成员变量是指针),但是没有copy constructor和assignment operator存在.这样如果出现两个类进行赋值的时候,有可能造成问题.
这个问题是由Effective C++ Item 11: Declare a copy constructor and an assignment operator for classes with dynamically allocated memory.来定义的.
最典型的例子就是我们的string类.上次在论坛还见到有人在问面试题,也是考这个的.
解决方法就是增加copy constructor和assignment operator.
如果真的实际情况中赋值的话,那么可以用Effective C++ Item 11中的一个方法:
You declare the functions (private, as it turns out), but you don't define (i.e., implement) them at all.
eg:
class CX
{
private:
// 以下即只声明但是不定义,这样就防止别人使用了
CX(const CX& right);
CX& operator = (const CX& right);
private:
int * m_n;
};