[Linux_C]004

來源為wiki的Operators in C and C++

方便未來 重載運算子 用
關於C++ operator介紹如下：

Arithmetic operators
Operator name		Syntax	Can overload	Included in C	Prototype examples
					As member of K
Basic assignment		a = b	Yes	Yes	R& K::operator =(S b);
Addition		a + b	Yes	Yes	R K::operator +(S b);
Subtraction		a - b	Yes	Yes	R K::operator -(S b);
Unary plus (integer promotion)		+a	Yes	Yes	R K::operator +();
Unary minus (additive inverse)		-a	Yes	Yes	R K::operator -();
Multiplication		a * b	Yes	Yes	R K::operator *(S b);
Division		a / b	Yes	Yes	R K::operator /(S b);
Modulo (integer remainder)		a % b	Yes	Yes	R K::operator %(S b);
Increment	Prefix	++a	Yes	Yes	R& K::operator ++();
	Postfix	a++	Yes	Yes	R K::operator ++(int);
					Note: C++ uses the unnamed dummy-parameter int to differentiate between prefix and suffix increment operators.
Decrement	Prefix	--a	Yes	Yes	R& K::operator --();
	Postfix	a--	Yes	Yes	R K::operator --(int);
					"Note: C++ uses the unnamed dummy-parameter int to differentiate between prefix and suffix decrement operators."
Comparison operators/relational operators
Operator name		Syntax	Can overload	Included in C	Prototype examples
					As member of K
Equal to		a == b	Yes	Yes	bool K::operator ==(S const& b);
Not equal to		a != b a not_eq b	Yes	Yes	bool K::operator !=(S const& b);
Greater than		a > b	Yes	Yes	bool K::operator >(S const& b);
Less than		a < b	Yes	Yes	bool K::operator <(S const& b);
Greater than or equal to		a >= b	Yes	Yes	bool K::operator >=(S const& b);
Less than or equal to		a <= b	Yes	Yes	bool K::operator <=(S const& b);
Logical operators
Operator name		Syntax	Can overload	Included in C	Prototype examples
					As member of K
Logical negation (NOT)		!a not a	Yes	Yes	R K::operator !();
Logical AND		a && b a and b	Yes	Yes	R K::operator &&(S b);
Logical OR		a || b a or b	Yes	Yes	R K::operator ||(S b);
Bitwise operators
Operator name		Syntax	Can overload	Included in C	Prototype examples
					As member of K
Bitwise NOT		~a compl a	Yes	Yes	R K::operator ~();
Bitwise AND		a & b a bitand b	Yes	Yes	R K::operator &(S b);
Bitwise OR		a | b a bitor b	Yes	Yes	R K::operator |(S b);
Bitwise XOR		a ^ b a xor b	Yes	Yes	R K::operator ^(S b);
Bitwise left shift		a << b	Yes	Yes	R K::operator <<(S b);
Bitwise right shift		a >> b	Yes	Yes	R K::operator >>(S b);
Member and pointer operators
Operator name		Syntax	Can overload	Included in C	Prototype examples
					As member of K
Array subscript		a[b]	Yes	Yes	R& K::operator [](S b);
Indirection ("object pointed to by a")		*a	Yes	Yes	R& K::operator *();
Address ("address of a")		&a	Yes	Yes	R K::operator &();
Structure dereference ("member b of object pointed to bya")		a->b	Yes	Yes	R* K::operator ->();
Structure reference ("member b of object a")		a.b	No	Yes	N/A
Object pointed to by member b of object pointed to by a		a->*b	Yes	No	R& K::operator ->*(S b);
Object pointed to by member b of object a		a.*b	No	No	N/A
Other operators
Operator name		Syntax	Can overload	Included in C	Prototype examples
					As member of K
Function call See Function object.		a(a1, a2)	Yes	Yes	R K::operator ()(S a, T b, ...);
Comma		a, b	Yes	Yes	R K::operator ,(S b);
Ternary conditional		a ? b : c	No	Yes	N/A
Scope resolution		a::b	No	No	N/A
User-defined literals since C++11		"a"_b	Yes	No	N/A
Conversion ( C-style cast)		(type) a type(a)	Yes	Yes	K::operator R();
					Note: for user-defined conversions, the return type implicitly and necessarily matches the operator name.
Size-of		sizeof (a) sizeof (type)	No	Yes	N/A
Size of parameter pack since C++11		sizeof...(Args)	No	No	N/A
Align-of since C++11		alignof (type) or _Alignof (type)	No	Yes	N/A
Allocate storage		new type	Yes	No	void* K::operator new(size_t x);
Allocate storage (array)		new type[n]	Yes	No	void* K::operator new[](size_t a);
Deallocate storage (delete returns void so it isn't strictly speaking an operator)		delete a	Yes	No	void K::operator delete(void *a);
Deallocate storage (array)		delete[] a	Yes	No	void K::operator delete[](void *a);
Type identification		typeid (a) typeid (type)	No	No	N/A
static_cast conversion		static_cast<type>(a)	No	No	N/A
dynamic_cast conversion		dynamic_cast<type>(a)	No	No	N/A
const_cast conversion		const_cast<type>(a)	No	No	N/A
reinterpret_cast conversion		reinterpret_cast<type>(a)	No	No	N/A
Exception check since C++11		noexcept(a)	No	No	N/A