重载赋值运算符 C++ 传递非常量参数

Question

I'm building my own data structures in C++ for university and I've a problem with "queue" data structure. In particular when I'm trying to overload the assignment operator like this:

Queue& operator=(Queue& C){

   if(this != &C){
     elements = new element_type[C.maxlength];
     maxlength = C.maxlength;
     length = C.length;
     head = C.head;

     if(!C.emptyQueue()){
       for(int i=0; i<length; i++){
         pushQueue(C.readQueue());
       }
       C.pushQueue(C.readQueue());
       C.popQueue();
     }
   }
   return *this;
}

the complier says "cannot bind non-const lvalue reference of type 'Queue&' to an rvalue of type 'Queue'" But, from the moment I need to modify the input parameter (cause to read every value from the queue and push it into the new queue, I need to pop every element) I think it's mandatory to pass it without const. Is there another way to do this or I'm missing something?

Answer 1

Your copy assignment operator is actually a move, not a copy assignment.

Use the move assignment:

Queue& operator=(Queue&& C){