C++ 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 | a++a-- | Suffix/postfix increment and decrement | |
| type()type{} | Functional cast | ||
| a() | Function call | ||
| a[] | Subscript | ||
| .-> | Member access | ||
| 3 | ++a--a | Prefix increment and decrement | Right-to-left | 
| +a-a | Unary plus and minus | ||
| !~ | Logical NOT and bitwise NOT | ||
| (type) | C-style cast | ||
| *a | Indirection (dereference) | ||
| &a | Address-of | ||
| sizeof | Size-of[note 1] | ||
| newnew[] | Dynamic memory allocation | ||
| deletedelete[] | Dynamic memory deallocation | ||
| 4 | .*->* | Pointer-to-member | Left-to-right | 
| 5 | a*ba/ba%b | Multiplication, division, and remainder | |
| 6 | a+ba-b | Addition and subtraction | |
| 7 | <<>> | Bitwise left shift and right shift | |
| 8 | <<= | For relational operators < and ≤ respectively | |
| >>= | For relational operators > and ≥ respectively | ||
| 9 | ==!= | For relational operators = and ≠ respectively | |
| 10 | a&b | Bitwise AND | |
| 11 | ^ | Bitwise XOR (exclusive or) | |
| 12 | | | Bitwise OR (inclusive or) | |
| 13 | && | Logical AND | |
| 14 | || | Logical OR | |
| 15 | a?b:c | Ternary conditional[note 2] | Right-to-left | 
| throw | throw operator | ||
| = | Direct assignment (provided by default for C++ classes) | ||
| +=-= | Compound assignment by sum and difference | ||
| *=/=%= | Compound assignment by product, quotient, and remainder | ||
| <<=>>= | Compound assignment by bitwise left shift and right shift | ||
| &=^=|= | Compound assignment by bitwise AND, XOR, and OR | ||
| 16 | , | Comma | Left-to-right | 
- ↑ The operand of sizeofcan't be a C-style type cast: the expressionsizeof (int) * pis unambiguously interpreted as(sizeof(int)) * p, but notsizeof((int)*p).
- ↑ 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 of the table above with a precedence will be bound tighter (as if by parentheses) to its arguments than any operator that is listed on a row further below it with a lower precedence. For example, the expressions std::cout << a & b and *p++ are parsed as (std::cout << a) & b and *(p++), and not as std::cout << (a & b) or (*p)++.
Operators that have the same precedence are bound to their arguments in the direction of their associativity. 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 of assignment, but a + b - c is parsed (a + b) - c and not a + (b - c) because of left-to-right associativity of addition and subtraction.
Associativity specification is redundant for unary operators and is only shown for completeness: unary prefix operators always associate right-to-left (delete ++*p is delete(++(*p))) and unary postfix operators always associate left-to-right (a[1][2]++ is ((a[1])[2])++). Note that the associativity is meaningful for member access operators, even though they are grouped with unary postfix operators: a.b++ is parsed (a.b)++ and not a.(b++).
Operator precedence is unaffected by operator overloading. For example, std::cout << a ? b : c; parses as (std::cout << a) ? b : c; because the precedence of arithmetic left shift is higher than the conditional operator.
[edit] Notes
Precedence and associativity are compile-time concepts and are independent from order of evaluation, which is a runtime concept.
The standard itself doesn't specify precedence levels. They are derived from the grammar.
const_cast, static_cast, dynamic_cast, reinterpret_cast, typeid, sizeof..., noexcept and alignof 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 ternary conditional and assignment operators differs between C and C++: in C, assignment is not allowed on the right-hand side of a ternary 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)).
[edit] See also
| Common operators | ||||||
|---|---|---|---|---|---|---|
| assignment | increment decrement | arithmetic | logical | comparison | member access | other | 
| a = b | ++a | +a | !a | a == b | a[b] | a(...) | 
| Special operators | ||||||
| static_cast converts one type to another related type  | ||||||
| C documentation for C operator precedence | 


