13
It is necessary to be careful of the meaning of such expressions as a + b * c
We may want the effect as either
(a + b) * c
or
a + (b * c)
All operators have a priority, and high priority operators are evaluated before lower priority ones. Operators of the same priority are evaluated from left to right, so that
a - b - c
is evaluated as
( a - b ) - c
as you would expect.
From high priority to low priority the order for all C operators (we have not met all of them yet) is:
() {} ->.
! ~ - * & sizeof cast ++ --
(these are right -> left)
* / %
+ -
< <= >= >
&
^
|
&&
||
?: (right -> left)
= + = - = (right -> left)
, (comma)
Thus
a < 10 &&2 *b < c
is interpreted as
( a < 10 ) &&( ( 2 *b ) < c )
and
a = b = spokes / spokes_per_wheel + spares;
as
a = (b = (spokes / spokes_per_wheel)+spares);