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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.
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 if no move constructor and move assignment operator 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.
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 ...
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).
For example, += and -= are often called plus equal(s) and minus equal(s), instead of the more verbose "assignment by addition" and "assignment by subtraction". The binding of operators in C and C++ is specified (in the corresponding Standards) by a factored language grammar, rather than a precedence table. This creates some subtle conflicts.
Additionally, due to the lack of garbage collection in C++, programs will frequently copy an object whenever the ownership and lifetime of a single shared object would be unclear. For example, inserting an object into a standard library collection (such as a std::vector) typically involves making and inserting a copy into the collection.
The C++ standard library instead provides a dynamic array (collection) that can be extended or reduced in its std::vector template class. The C++ standard does not specify any relation between new / delete and the C memory allocation routines, but new and delete are typically implemented as wrappers around malloc and free. [6]