Operator precedence
Operator precedence is a set of rules that determines the order in which mathematical and logical operators are evaluated in an expression. Operators with higher precedence are evaluated first, while operators with lower precedence are evaluated later. In programming languages, the order of evaluation can impact the outcome of an expression, so understanding operator precedence is essential for writing correct and efficient code. Examples of operators with high precedence include exponentiation and negation, while examples of operators with low precedence include addition and multiplication. It's important to note that parentheses can be used to override the default precedence and force certain operators to be evaluated first.
| 运算符 | 优先级 |
|---|---|
| postfix | expr++ expr-- |
| unary | ++expr --expr +expr -expr ~ ! |
| multiplicative | * / % |
| additive | + - |
| shift | << >> >>> |
| relational | < > <= >= instanceof |
| equality | == != |
| bitwise AND | & |
| bitwise exclusive OR | ^ |
| bitwise inclusive OR | | |
| logical AND | && |
| logical OR | || |
| ternary | ? : |
| assignment | = += -= *= /= %= &= ^= |= <<= >>= >>>= |
| Precedence | Operator | Description | Associativity |
|---|---|---|---|
| 1 | ::
|
Scope resolution | Left-to-right |
| 2 | ++ --
|
Suffix/postfix increment and decrement | |
()
|
Function call | ||
[]
|
Array subscripting | ||
.
|
Element selection by reference | ||
−>
|
Element selection through pointer | ||
| 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 | ||
delete, delete[]
|
Dynamic memory deallocation | ||
| 4 | .* ->*
|
Pointer to member | Left-to-right |
| 5 | * / %
|
Multiplication, division, and 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 (for exceptions) | |
| 18 | ,
|
Comma | Left-to-right |
| Precedence | Operator | Description | Associativity |
|---|---|---|---|
| 1 | ++ --
|
Suffix/postfix increment and decrement | Left-to-right |
()
|
Function call | ||
[]
|
Array subscripting | ||
.
|
Structure and union member access | ||
−>
|
Structure and union member access through pointer | ||
(type){list}
|
Compound literal(C99) | ||
| 2 | ++ --
|
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 | ||
_Alignof
|
Alignment requirement(C11) | ||
| 3 | * / %
|
Multiplication, division, and remainder | Left-to-right |
| 4 | + −
|
Addition and subtraction | |
| 5 | << >>
|
Bitwise left shift and right shift | |
| 6 | < <=
|
For relational operators < and ≤ respectively | |
> >=
|
For relational operators > and ≥ respectively | ||
| 7 | == !=
|
For relational = and ≠ respectively | |
| 8 | &
|
Bitwise AND | |
| 9 | ^
|
Bitwise XOR (exclusive or) | |
| 10 | |
|
Bitwise OR (inclusive or) | |
| 11 | &&
|
Logical AND | |
| 12 | ||
|
Logical OR | |
| 13 | ?:
|
Ternary conditional | Right-to-Left |
| 14 | =
|
Simple assignment | |
+= −=
|
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 | ||
| 15 | ,
|
Comma | Left-to-right |
| 结合方向 | 运算符 | 附加信息 |
|---|---|---|
| 非结合 | clone new |
clone 和 new |
| 左 | [ |
array() |
| 非结合 | ++ -- |
递增／递减运算符 |
| 非结合 | ~ - (int) (float) (string) (array) (object) (bool) @ |
类型 |
| 非结合 | instanceof |
类型 |
| 右结合 | ! |
逻辑操作符 |
| 左 | * / % |
算术运算符 |
| 左 | + - . |
算术运算符 和 字符串运算符 |
| 左 | << >> |
位运算符 |
| 非结合 | < <= > >= <> |
比较运算符 |
| 非结合 | == != === !== |
比较运算符 |
| 左 | & |
位运算符 和 引用 |
| 左 | ^ |
位运算符 |
| 左 | | |
位运算符 |
| 左 | && |
逻辑运算符 |
| 左 | || |
逻辑运算符 |
| 左 | ? : |
三元运算符 |
| 右 |
= += -= *= /= .= %= &= |= ^= <<= >>=
|
赋值运算符 |
| 左 | and |
逻辑运算符 |
| 左 | xor |
逻辑运算符 |
| 左 | or |
逻辑运算符 |
| 左 | , |
多处用到 |
这个表给出Python的运算符优先级（从低到高）.
从最低的优先级（最松散地结合）到最高的优先级（最紧密地结合）。
这意味着在一个表达式中，Python会首先计算表中较下面的运算符，然后在计算列在表上部的运算符。
| 运算符 | 描述 |
|---|---|
lambda |
Lambda表达式 |
or |
布尔“或” |
and |
布尔“与” |
not x |
布尔“非” |
in，not in |
成员测试 |
is，is not |
同一性测试 |
<，<=，>，>=，!=，== |
比较 |
| |
按位或 |
^ |
按位异或 |
& |
按位与 |
<<，>> |
移位 |
+，- |
加法与减法 |
*，/，% |
乘法、除法与取余 |
+x，-x |
正负号 |
~x |
按位翻转 |
** |
指数 |
x.attribute |
属性参考 |
x[index] |
下标 |
x[index:index] |
寻址段 |
f(arguments...) |
函数调用 |
(experession,...) |
绑定或元组显示 |
[expression,...] |
列表显示 |
{key:datum,...} |
字典显示 |
'expression,...' |
字符串转换 |
