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 | ++ -- | Suffix/postfix increment and decrement | Left-to-right |
() | Function call | ||
[] | Array subscripting | ||
. | Structure and union member access | ||
-> | Structure and union member access through pointer | ||
(type){list} | Compound literal(C99) | ||
| 2 | ++ -- | 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 | ||
_Alignof | 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 1] | ?: | Ternary conditional[note 2] | 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 | ||
| 15 | , | Comma | Left-to-right |
- Fictional precedence level, see Notes below
- 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 expression *p++ is parsed as *(p++), and not as (*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.
Notes
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: assignment is never allowed to appear on the right hand side 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.
References
- C11 standard (ISO/IEC 9899:2011):
- A.2.1 Expressions
- C99 standard (ISO/IEC 9899:1999):
- A.2.1 Expressions
- C89/C90 standard (ISO/IEC 9899:1990):
- A.1.2.1 Expressions
See Also
Order of evaluation of operator arguments at run time.
| Common operators | ||||||
|---|---|---|---|---|---|---|
| assignment | increment decrement | arithmetic | logical | comparison | member access | other |
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C++ documentation for C++ operator precedence |
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