c++ - 谁能帮我看下下面这段代码，多项式乘法和+=操作运行不了，求助啊，到底错在哪了？

Answer 1

After taking a general look, I have a few questions.

1. There are problems with the definition of several compound assignment operators, such as:

   Polynomial& operator+=(const Polynomial&x) {
     return *this+ x;  // 此处返回了局部变量的引用，是未定义行为
   }

   The reason is that *this+x calls Polynomial::operator+ and returns a new Polynomial variable. This variable is a local variable of operator+=, and the return value of operator+= is a reference to this new variable, so it is Undefined behavior. Several other compound assignment operators are similar.

2. The implementation of several operator overloading is not very good, such as:

   • Only one of operator!= and operator== needs to be implemented specifically, and the other should call the implemented one;

   • operator+= should be implemented specifically, and operator+ should call operator+=. Please refer to the reason here. Subtraction and multiplication are similar;

3. When the constructor initializes members, try to use the member initialization list to assign initial values.