C++ 运算符优先级列表
http://en.cppreference.com/w/cpp/language/operator_precedence
The following table lists the precedence and associativity of C++ operators.
Operators are listed top to bottom, in descending precedence.
| 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 |
= |
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 | ||
| 16 | throw |
Throw operator (for exceptions) | |
| 17 | , |
Comma | Left-to-right |
When parsing an expression, an operator which is listed on some row
will be bound tighter (as if by parentheses) to its arguments than
any operator that is listed on a row further below it. For example,
the expressions std::cout<<a&b is parsed as (std::cout<<a)&b, not asstd::cout<<(a&b).
the expressions *p++ is parsed as *(p++), not (*p)++.
Operators that are in the same cell (there may be several rows of operators listed in a cell)
are evaluated with the same precedence, in the given direction. For example,
the expression a=b=c is parsed as a=(b=c), and not as (a=b)=c
because of right-to-left associativity.
An operator's precedence is unaffected by overloading.
Ｃ语言中，运算符的运算优先级共分为15级。1级最高，15级最低。
在表达式中，优先级较高的先于优先级较低的进行运算。
而在一个运算量两侧的运算符优先级相同时， 则按运算符的结合性所规定的结合方向处理。
Ｃ语言中各运算符的结合性分为两种，即左结合性(自左至右)和右结合性(自右至左)。
例如算术运算符的结合性是自左至右，即先左后右。
如有表达式x-y+z则y应先与“-”号结合， 执行x-y运算，然后再执行+z的运算。
这种自左至右的结合方向就称为“左结合性”。
而自右至左的结合方向称为“右结合性”。
最典型的右结合性运算符是赋值运算符。
如x=y=z,由于“=”的右结合性，应先执行y=z再执行x=(y=z)运算。
