ch 5 Expression & conversion

5.3 bitwise 為bit操作運算值; 

such as: << , & , |

5.5 Increment and Decrement

有分為prefix and postfix , such as ++i  or i++
注意postfix 同一行中,會用先前值來處理
例如 :

int count=0;
vector.push(count ++) //存值為 0
int count=0;
vector.push(++count ) //存值為 1

5.10 compound Expressions 複合式

主要有兩點考量1.優先值 precedence 2.結合順序 associativity

http://en.cppreference.com/w/cpp/language/operator_precedence

Precedence	Operator	Description	Associativity
1	::	Scope resolution	Left-to-right
2	a++   a--	Suffix/postfix increment and decrement
	type()   type{}	Functional cast
	a()	Function call
	a[]	Subscript
	.   ->	Member access
3	++a   --a	Prefix increment and decrement	Right-to-left
	+a   -a	Unary plus and minus
	!   ~	Logical NOT and bitwise NOT
	(type)	C-style cast
	*a	Indirection (dereference)
	&a	Address-of
	sizeof	Size-of[note 1]
	new   new[]	Dynamic memory allocation
	delete   delete[]	Dynamic memory deallocation
4	.*   ->*	Pointer-to-member	Left-to-right
5	a*b   a/b   a%b	Multiplication, division, and remainder
6	a+b   a-b	Addition and subtraction
7	<<   >>	Bitwise left shift and right shift
8	<   <=	For relational operators < and ≤ respectively
	>   >=	For relational operators > and ≥ respectively
9	==   !=	For relational operators = and ≠ respectively
10	a&b	Bitwise AND
11	^	Bitwise XOR (exclusive or)
12	|	Bitwise OR (inclusive or)
13	&&	Logical AND
14	||	Logical OR
15	a?b:c	Ternary conditional[note 2]	Right-to-left
	throw	throw operator
	=	Direct assignment (provided by default for C++ classes)
	+=   -=	Compound assignment by sum and difference
	*=   /=   %=	Compound assignment by product, quotient, and remainder
	<<=   >>=	Compound assignment by bitwise left shift and right shift
	&=   ^=   |=	Compound assignment by bitwise AND, XOR, and OR
16	,	Comma	Left-to-right

與優先順序有關的例子:
ex1:

vector<int> testVector;

testVector.push_back(1);

vector<int> *pVector=&testVector;

(*pVector)[0] // correct

*vector[0] //error

5.12 Type Conversion

1. Implicit 隱式 2.Explicit 顯式 3.Arithmetic 運算

1.Implicit conversion

int ivalue=3.14; // double -> int


2.Explicit  conversion

static_cast, dynamic_cast, const_cast, reinterpret_cast

3.Arithmetic  conversion
比int 小的 such as : char ,short, will promte to int;(integral promotions)
例如:
int ivalue=1; double dval=3.111;

ivalue+dval 則ivalue 變為double