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The move assignment operator, like most C++ operators, can be overloaded. Like the copy assignment operator it is a special member function . If the move assignment operator is not explicitly defined, the compiler generates an implicit move assignment operator ( C++11 and newer) provided that copy / move constructors , copy assignment operator ...
In the C++ programming language, the assignment operator, =, is the operator used for assignment.Like most other operators in C++, it can be overloaded.. The copy assignment operator, often just called the "assignment operator", is a special case of assignment operator where the source (right-hand side) and destination (left-hand side) are of the same class type.
Copy constructor if no move constructor and move assignment operator are explicitly declared. If a destructor is declared generation of a copy constructor is deprecated (C++11, proposal N3242 [2]). Move constructor if no copy constructor, copy assignment operator, move assignment operator and destructor are explicitly declared.
Copy assignment operator – assign all the object's members from the corresponding members of the assignment operator's argument, calling the copy assignment operators of the object's class-type members, and doing a plain assignment of all non-class type (e.g. int or pointer) data members.
In this case chain assignment can be implemented by having a right-associative assignment, and assignments happen right-to-left. For example, i = arr[i] = f() is equivalent to arr[i] = f(); i = arr[i]. In C++ they are also available for values of class types by declaring the appropriate return type for the assignment operator.
C++ objects in general behave like primitive types, so to copy a C++ object one could use the '=' (assignment) operator. There is a default assignment operator provided for all classes, but its effect may be altered through the use of operator overloading. There are dangers when using this technique (see slicing).
A unique_ptr explicitly prevents copying of its contained pointer (as would happen with normal assignment), but the std::move function can be used to transfer ownership of the contained pointer to another unique_ptr. A unique_ptr cannot be copied because its copy constructor and assignment operators are explicitly deleted.
In C++11, a move constructor of std::vector<T> that takes an rvalue reference to an std::vector<T> can copy the pointer to the internal C-style array out of the rvalue into the new std::vector<T>, then set the pointer inside the rvalue to null. Since the temporary will never again be used, no code will try to access the null pointer, and ...