Operator precedence

Operator precedence is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

This page uses content from Wikipedia. The original article was at Operators in C and C++. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance)

The following contains tables of precedence and associativity of all the operators various languages. Operators are listed top to bottom, in descending precedence. Descending precedence refers to the priority of evaluation. Considering an expression, an operator which is listed on some row will be evaluated prior to any operator that is listed on a row further below it. 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.

C++

The following is a table that lists the precedence and associativity of all the operators in the C and C++ languages. An operator's precedence is unaffected by overloading.

Precedence	Operator	Description	Associativity
1 highest	::	Scope resolution (C++ only)	Left-to-right
2	++	Suffix increment
	--	Suffix decrement
	()	Function call
	[]	Array subscripting
	.	Element selection by reference
	->	Element selection through pointer
	typeid()	Run-time type information (C++ only) (see typeid)
	const_cast	Type cast (C++ only) (see const cast)
	dynamic_cast	Type cast (C++ only) (see dynamic cast)
	reinterpret_cast	Type cast (C++ only) (see reinterpret cast)
	static_cast	Type cast (C++ only) (see static cast)
3	++	Prefix increment	Right-to-left
	--	Prefix decrement
	+	Unary plus
	-	Unary minus
	!	Logical NOT
	~	Bitwise NOT
	(type)	Type cast
	*	Indirection (dereference)
	&	Address-of
	sizeof	Size-of
	new, new[]	Dynamic memory allocation (C++ only)
	delete, delete[]	Dynamic memory deallocation (C++ only)
4	.*	Pointer to member (C++ only)	Left-to-right
	->*	Pointer to member (C++ only)
5	*	Multiplication
	/	Division
	%	Modulo (remainder)
6	+	Addition
	-	Subtraction
7	<<	Bitwise left shift
	>>	Bitwise right shift
8	<	Less than
	<=	Less than or equal to
	>	Greater than
	>=	Greater than or equal to
9	==	Equal to
	!=	Not equal to
10	&	Bitwise AND
11	^	Bitwise XOR (exclusive or)
12	|	Bitwise OR (inclusive or)
13	&&	Logical AND
14	||	Logical OR
15	?:	Ternary conditional (see ?:)	Right-to-left
16	=	Direct assignment
	+=	Assignment by sum
	-=	Assignment by difference
	*=	Assignment by product
	/=	Assignment by quotient
	%=	Assignment by remainder
	<<=	Assignment by bitwise left shift
	>>=	Assignment by bitwise right shift
	&=	Assignment by bitwise AND
	^=	Assignment by bitwise XOR
	|=	Assignment by bitwise OR
17	throw	Throw operator (exceptions throwing, C++ only)
18	,	Comma	Left-to-right

J

Precedence	Grammatical classification	Associativity
highest	conjunctions	long left scope
	adverbs
lowest	verbs	long right scope

See http://www.jsoftware.com/help/dictionary/partsofspeech.htm for tokens in each grammatical class.

Note that other parts of speech do not have any precedence, because they are not "operators".

Note that this is an imprecise statement of the grammatical rules. For a complete treatment, see http://www.jsoftware.com/help/dictionary/dicte.htm

Here's an informal treatment of the grammar:

Conjunctions require a left and right argument, either of which may be a noun or a verb. If one argument is omitted the conjunction is curried with the remaining argument, forming an adverb (if the right argument is omitted, the precedence of the conjunction is treated as lower than the precedence of a verb).

Adverbs require a single left argument, which may be a noun or a verb.

Verbs require a right argument which must be a noun and may accept an optional left argument (which must also be a noun). Unless we're working with a dangling (rightmost) conjunction, verbs have lower precedence than adverbs and conjunctions.

Nouns are not operators and accept no arguments.

The result of a verb must be a noun.

The result of an adverb or a conjunction can have any one of these grammatical classifications, and verb results are typical (and, thus, the result of an adverb or a conjunction may accept further arguments). Adverbs and conjunctions serve a role analogous to that of macros in other languages.

OCaml

This table contains the precedence and associativity of operators and other expression constructs in OCaml, including user-defined operators.

PHP

Operator Precedence

Python

See this table and the whole page for details on Python version 3.x

Tcl

Tcl only supports operators within an expression context (such as the expr command):

Precedence	Operator	Description
highest	- + ~ !	Unary minus, unary plus, bit-wise NOT, logical NOT. None of these operators may be applied to string operands, and bit-wise NOT may be applied only to integers.
	**	Exponentiation. Valid for any numeric operands. Right-to-left associative.
	* / %	Multiply, divide, remainder. None of these operators may be applied to string operands, and remainder may be applied only to integers. The remainder will always have the same sign as the divisor and an absolute value smaller than the divisor.
	+ -	Add and subtract. Valid for any numeric operands.
	<< >>	Left and right shift. Valid for integer operands only. A right shift always propagates the sign bit.
	< > <= >=	Boolean less, greater, less than or equal, and greater than or equal. Each operator produces 1 if the condition is true, 0 otherwise. These operators may be applied to strings as well as numeric operands, in which case string comparison is used.
	== !=	Boolean equal and not equal. Each operator produces a zero/one result. Valid for all operand types.
	eq ne	Boolean string equal and string not equal. Each operator produces a zero/one result. The operand types are interpreted only as strings.
	in ni	List containment and negated list containment. Each operator produces a zero/one result and treats its first argument as a string and its second argument as a Tcl list. The in operator indicates whether the first argument is a member of the second argument list; the ni operator inverts the sense of the result.
	&	Bit-wise AND. Valid for integer operands only.
	^	Bit-wise exclusive OR. Valid for integer operands only.
	|	Bit-wise OR. Valid for integer operands only.
	&&	Logical AND. Produces a 1 result if both operands are non-zero, 0 otherwise. Valid for boolean and numeric (integers or floating-point) operands only. Evaluates its second operand lazily.
	||	Logical OR. Produces a 0 result if both operands are zero, 1 otherwise. Valid for boolean and numeric (integers or floating-point) operands only. Evaluates its second operand lazily.
lowest	x ? y : z	If-then-else, as in C. If x evaluates to non-zero, then the result is the value of y. Otherwise the result is the value of z. The x operand must have a boolean or numeric value. Evaluates its second and third operands lazily.