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] | ||
new new[]
|
Dynamic memory allocation | ||
delete delete[]
|
Dynamic memory deallocation | ||
| 4 | .* ->*
|
Pointer-to-member | Left-to-right |
| 5 | a*b a/b a%b
|
Multiplication, division, and remainder | |
| 6 | a+b a-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.
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)).
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
|