最近总是由于不清楚运算符优先级不小心写错代码，每次都去查cppreference。现在把cppreference内容拷贝至此，方便查询。 这里面最值得注意的是<<（移位）优先级低于+/-（加减），!（逻辑非）++/--（自增/自减）+/-（正负）优先级低于->运算符。

优先级与结合性

下表列出了C++运算符的优先级和结合性。从上到下，运算符的优先级逐渐减弱.

Precedence Operator Description Associativity
1 :: 作用域解析 Left-to-right
2 ++   -- 后缀 自增、自减
() 函数调用
[] 数组下标
. 通过引用选择成员
−> 通过指针选择成员
3 ++   -- 前缀 自增、自减 Right-to-left
+   − 正、负
!   ~ 逻辑非、按位非
(type) 显式类型转换
* 解引用
& 取地址
sizeof 取对象大小
new, new[] 动态内存分配
delete, delete[] 动态内存去分配
4 .*   ->* 成员指针运算符 Left-to-right
5 *   /   % 乘、除、求余
6 +   − 加、减
7 <<   >> 按位左移、按位右移
8 <   <= 小于、小于或等于
>   >= 大于、大于或等于
9 ==   != 等于、不等于
10 & 按位与
11 ^ 按位异或
12 | 按位或
13 && 逻辑与
14 || 逻辑或
15 ?: 三目运算符 Right-to-left
= 赋值
+=   −= Assignment by sum and difference
*=   /=   %= Assignment by product, quotient, and remainder
<<=   >>= Assignment by bitwise left shift and right shift
&=   ^=   |= Assignment by bitwise AND, XOR, and OR
throw Throw operator (for exceptions)
17 , Comma Left-to-right

运算符列表

Common operators
assignment increment
decrement 		arithmetic logical comparison member
access 		other

a = b
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 (since C++11)
typeid queries the type information of a type
noexcept checks if an expression can throw an exception (since C++11)
alignof queries alignment requirements of a type (since C++11)

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