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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. It is one of the special member functions, which means that a default version of it is generated automatically by the compiler if the programmer does not declare one. The default version performs a memberwise copy, where each member is copied by its own copy assignment operator (which may also be programmer-declared or compiler-generated). The copy assignment operator differs from the copy constructor in that it must clean up the data members of the assignment's target (and correctly handle self-assignment) whereas the copy constructor assigns values to uninitialized data members. For example: My_Array first; // initialization by default constructor My_Array second(first); // initialization by copy constructor My_Array third = first; // Also initialization by copy constructor second = third; // assignment by copy assignment operator ==Return value of overloaded assignment operator== The language permits an overloaded assignment operator to have an arbitrary return type (including void). However, the operator is usually defined to return a reference to the assignee. This is consistent with the behavior of assignment operator for built-in types (returning the assigned value) and allows for using the operator invocation as an expression, for instance in control statements or in chained assignment. Also, the C++ Standard Library requires this behavior for some user-supplied types.〔Working Draft, Standard for Programming Language C++, Section 17.6.3.1, Table 23; http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf〕抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Assignment operator (C++)」の詳細全文を読む スポンサード リンク
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