< >>

left to right

<= > >=

left to right

== !=

left to right

&

left to right

^

left to right

|

left to right

&&

left to right

||

left to right

?:

right to left

= += -= *= /= %= &= ^= |= <<= >>=

right to left

,

left to right

Unary & +, -, and * have higher precedence than the binary forms.

Table 2.1: Precedence and Associativity of Operators

Note that the precedence of the bitwise operators &, ^, and | falls below == and !=. This implies that bit-testing expressions like

if ((x & MASK) == 0) ...

must be fully parenthesized to give proper results.

C, like most languages, does not specify the order in which the operands of an operator are evaluated. (The exceptions are &&, ||, ?:, and '.) For example, in a statement like

x = f() + g();

f

may be evaluated before

g

or vice versa; thus if either

f

or

g

alters a variable on which the other depends,

x

can depend on the order of evaluation. Intermediate results can

be stored in temporary variables to ensure a particular sequence.

Similarly, the order in which function arguments are evaluated is not specified, so the statement

printf("%d %dn", ++n, power(2, n)); /* WRONG */

can produce different results with different compilers, depending on whether

n

is incremented before

power

is called. The solution, of

course, is to write

++n;

printf("%d %dn", n, power(2, n));