Assignment operators

From Cppreference

Assignment operators modify the value of the object.

Operator name	Syntax	Overloadable	Prototype examples (for class T)
Operator name	Syntax	Overloadable	Inside class definition	Outside class definition
basic assignment	`a = b`	Yes	T& T::operator =(const T2 &b);	N/A
move assignment (C++11)	`a = rvalue`	Yes	T& T::operator =(const T2 &&b);	N/A
addition assignment	`a += b`	Yes	T& T::operator +=(const T2 &b);	T& operator +=(T &a, const T2 &b);
subtraction assignment	`a -= b`	Yes	T& T::operator -=(const T2 &b);	T& operator -=(T &a, const T2 &b);
multiplication assignment	`a *= b`	Yes	T& T::operator *=(const T2 &b);	T& operator *=(T &a, const T2 &b);
division assignment	`a /= b`	Yes	T& T::operator /=(const T2 &b);	T& operator /=(T &a, const T2 &b);
modulo assignment	`a %= b`	Yes	T& T::operator %=(const T2 &b);	T& operator %=(T &a, const T2 &b);
bitwise AND assignment	`a &= b`	Yes	T& T::operator &=(const T2 &b);	T& operator &=(T &a, const T2 &b);
bitwise OR assignment	`a \|= b`	Yes	T& T::operator \|=(const T2 &b);	T& operator \|=(T &a, const T2 &b);
bitwise XOR assignment	`a ^= b`	Yes	T& T::operator ^=(const T2 &b);	T& operator ^=(T &a, const T2 &b);
bitwise left shift assignment	`a <<= b`	Yes	T& T::operator <<=(const T2 &b);	T& operator <<=(T &a, const T2 &b);
bitwise right shift assignment	`a >>= b`	Yes	T& T::operator >>=(const T2 &b);	T& operator >>=(T &a, const T2 &b);
Notes All operators usually return `*this`. However, essentially any value and any type can be returned (including void, i.e. no return value), yet this is unintuitive and defeats the purpose of the operators. `T2` can be any type including `T`

[edit] Explanation

basic assignment operator replaces the contents of the object a with those of b

move assignment operator replaces the contents of the object a with those of b while minimizing copying overhead (no deep copy is performed). It complements the basic assignment operator. (C++11 feature)

Other assignment operators modify the contents of the object. Usually they are overloaded in classes performing mathematical operations.

[edit] See also

Operator precedence

Common operators
assignment	increment decrement	arithmetic	logical	comparison	member access	other
a = b a = rvalue a += b a -= b a *= b a /= b a %= b a &= b a \|= b a ^= b a <<= b a >>= b	++a --a a++ a--	+a -a a + b a - b a * b a / b a % b ~a a & b a \| b a ^ b a << b a >> b	!a a && b a \|\| b	a == b a != b a < b a > b a <= b a >= b	a[b] a &a a->b a.b a->b a.*b	a(...) a, b (type) a ? :
Special operators
`static_cast` converts one type to another compatible type `dynamic_cast` converts virtual base class to derived class `const_cast` converts type to compatible type with different cv qualifiers `reinterpret_cast` converts type to incompatible type `new` allocates memory `delete` deallocates memory `sizeof` queries the size of a type `sizeof...` queries the size of a parameter pack (C++11 feature) `typeid` queries the type information of a type `noexcept` checks if an expression can throw an exception (C++11 feature) `alignof` queries alignment requirements of a type (C++11 feature)