Precedence, Associativity

Summary: Operators

Operators seen thus far

• Arithmetic (unary and binary)

• Comparison

• Boolean

• Bitwise

• Assignment (combined)

• Conditional expression

Operators: Precedence und Associativity (1)

Operator Table

• Ordered by precedence (strongest binding first)

• Left- or right associativity at equal precedence

Attention

• Precedence und associativity often not intuitive

  • E.g.: x | y < z is evaluated as x | (y < z)

• ⟶ difficult to comprehend and remember

• Use braces to make precedence explicit

• ⟶ for yourself and for your successor

Operators: Precedence und Associativity (2)

	Operator	Associativity
highest	(), [], ->, .	left
	!, ~, ++, --, +, -, *, &, (type) (cast), sizeof	right (unary operators)
	*, /, %	left
	+, -	left
	<<, >>	left
	<, <=, >, >=	left
	==, !=	left
	&	left
	^	left
	|	left
	&&	left
	||	left
	?:	right
	=, +=, -=, *=, /=, %=, &=, ^=, |=, <<=, >>=	right
lowest	,	left

More Warnings

The order in which operands are evaluated is unspecified (compiler dependent)

x = f() + g(); /* DANGER! */

The order in which function parameters are evaluated is unspecified (compiler dependent)

f(++i, i); /* DANGER! */
a[i] = i++; /* MORE DANGER */