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WordPress数据库错误: [Got error 28 from storage engine]
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C++操作符的优先级 – Crazy knowledge base
Crazy knowledge base

C++操作符的优先级

Precedence Operator Description Associativity
1 :: Scope resolution (C++ only) Left-to-right
2 ++ — Suffix/postfix increment and decrement
() Function call
[] Array subscripting
. Element selection by reference
-> Element selection through pointer
typeid() Run-time type information (see typeid)
const_cast Type cast (see const_cast)
dynamic_cast Type cast (see dynamic_cast)
reinterpret_cast Type cast (see explicit_cast)
static_cast Type cast (see static_cast)
3 ++ — Prefix increment and decrement Right-to-left
+ – Unary plus and minus
! ~ Logical NOT and bitwise NOT
(type) Type cast
* Indirection (dereference)
& Address-of
sizeof Size-of
new, new[] Dynamic memory allocation (C++ only)
delete, delete[] Dynamic memory deallocation (C++ only)
4 .* ->* Pointer to member (C++ only) Left-to-right
5 * / % Multiplication, division, and modulus (remainder)
6 + – Addition and subtraction
7 << >> Bitwise left shift and right shift
8 < <= For relational operators < and ≤ respectively
> >= For relational operators > and ≥ respectively
9 == != For relational = and ≠ respectively
10 & Bitwise AND
11 ^ Bitwise XOR (exclusive or)
12 | Bitwise OR (inclusive or)
13 && Logical AND
14 || Logical OR
15 ?: Ternary conditional Right-to-Left
16 = Direct assignment (provided by default for C++ classes)
+= -= 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
17 throw Throw operator (exceptions throwing, C++ only)
18 , Comma Left-to-right

记忆方法:
–摘自《C语言程序设计实用问答》 -吕凤翥 吕 涛著
问题:如何记住运算符的15种优先级和结合性?
解答:C语言中运算符种类比较繁多,优先级有15种,结合性有两种。
如何记忆两种结合性和15种优先级?下面讲述一种记忆方法。
结合性有两种,一种是自左至右,另一种是自右至左,大部分运算符的结合性是自左至右,只有单目运算符、三目运算符的赋值运算符的结合性自右至左。
优先级有15种。记忆方法如下:
记住一个最高的:构造类型的元素或成员以及小括号。
记住一个最低的:逗号运算符。
剩余的是一、二、三、赋值。
意思是单目、双目、三目和赋值运算符。
在诸多运算符中,又分为:
算术、关系、逻辑。
两种位操作运算符中,移位运算符在算术运算符后边,逻辑位运算符在逻辑运算符的前面。再细分如下:
算术运算符分 *,/,%高于+,-。
关系运算符中,》,》=,《,〈=高于==,!=。
逻辑运算符中,除了逻辑求反(!)是单目外,逻辑与(&&)高于逻辑或(||)。
逻辑位运算符中,除了逻辑按位求反(~)外,按位与(&)高于按位半加(^),高于按位或(|)。
这样就将15种优先级都记住了,再将记忆方法总结如下:
去掉一个最高的,去掉一个最低的,剩下的是一、二、三、赋值。双目运算符中,顺序为算术、关系和逻辑,移位和逻辑位插入其中。

C++操作符的优先级

WordPress数据库错误: [Got error 28 from storage engine]
SELECT t.*, tt.* FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ('category') AND tr.object_id IN (249) ORDER BY t.name ASC

WordPress数据库错误: [Got error 28 from storage engine]
SELECT t.*, tt.* FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ('category') AND tr.object_id IN (251) ORDER BY t.name ASC

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