The following table lists the precedence and associativity of C operators. Operators are listed top to bottom, in descending precedence.
|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|
| ||Compound literal(C99)|
|2|| ||Prefix increment and decrement||Right-to-left|
| ||Unary plus and minus|
| ||Logical NOT and bitwise NOT|
| ||Type cast|
| ||Indirection (dereference)|
| ||Size-of[note 1]|
| ||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[note 2]|| ||Ternary conditional[note 3]||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|
sizeofcan't be a type cast: the expression
sizeof (int) * pis unambiguously interpreted as
(sizeof(int)) * p, but not
:) is parsed as if parenthesized: its precedence relative to
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 expression
*p++ is parsed as
*(p++), and not as
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.
Precedence and associativity are independent from order of evaluation.
The C language standard doesn't specify operator precedence. It specifies the language grammar, and the precedence table is derived from it to simplify understanding. There is a part of the grammar that cannot be represented by a precedence table: an assignment-expression is not allowed as the right hand operand of a conditional operator, so
e = a < d ? a++ : a = d is an expression that cannot be parsed, and therefore relative precedence of conditional and assignment operators cannot be described easily.
However, many C compilers use non-standard expression grammar where
?: is designated higher precedence than
=, which parses that expression as
e = ( ((a < d) ? (a++) : a) = d ), which then fails to compile due to semantic constraints:
?: is never lvalue and
= requires a modifiable lvalue on the left. This is the table presented on this page.
Note that this is different in C++, where the conditional operator has the same precedence as assignment.
Associativity specification is redundant for unary operators and is only shown for completeness: unary prefix operators always associate right-to-left (
sizeof ++*p is
sizeof(++(*p))) and unary postfix operators always associate left-to-right (
((a))++). 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
Order of evaluation of operator arguments at run time.
|assignment|| increment |
|arithmetic||logical||comparison|| member |
| || || || || || ||
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.