C++运算符优先级

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.

PrecedenceOperatorDescriptionAssociativity1::Scope resolutionLeft-to-right2++   --Suffix/postfix increment and decrement()Function call[]Array subscripting.Element selection by reference->Element selection through pointer3++   --Prefix increment and decrementRight-to-left+   -Unary plus and minus!   ~Logical NOT and bitwise NOT(type)Type cast*Indirection (dereference)&Address-ofsizeofSize-ofnew, new[]Dynamic memory allocationdelete, delete[]Dynamic memory deallocation4.*   ->*Pointer to memberLeft-to-right5*   /   %Multiplication, division, and remainder6+   -Addition and subtraction7<<   >>Bitwise left shift and right shift8<   <=For relational operators < and ≤ respectively>   >=For relational operators > and ≥ respectively9==   !=For relational = and ≠ respectively10&Bitwise AND11^Bitwise XOR (exclusive or)12|Bitwise OR (inclusive or)13&&Logical AND14||Logical OR15?:Ternary conditional^[1]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 OR16throwThrow operator (for exceptions)17,CommaLeft-to-right

[1]The expression in the middle of the conditional operator (between ? and :) is parsed as if parenthesized: its precedence relative to ?: is ignored.

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&band *p++ are parsed as (std::cout<<a)&b and *(p++), and not as std::cout<<(a&b) or (*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.

Operator precedence is unaffected by operator overloading.

Notes

Precedence and associativity are independent from order of evaluation.

The standard itself doesn't specify precedence levels. They are derived from the grammar.

const_cast, static_cast, dynamic_cast, reinterpret_cast and typeid are not included since they are never ambiguous.

Some of the operators have alternate spellings (e.g., and for &&, or for ||, not for !, etc.).

Relative precedence of the conditional and assignment operators differs between C and C++: in C, assignment is not allowed on the right hand side of a conditional operator, so e = a < d ? a++ : a = d cannot be parsed. Many C compilers use a modified grammar where ?: has higher precedence than =, which parses that as e = ( ((a < d) ? (a++) : a) = d ) (which then fails to compile because ?: is never lvalue in C and = requires lvalue on the left). In C++, ?: and = have equal precedence and group right-to-left, so that e = a < d ? a++ : a = d parses as e = ((a < d) ? (a++) : (a = d)).

See also

Common operatorsassignmentincrement
decrementarithmeticlogicalcomparisonmember
accessother

a = b
a = rvalue
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)