1# ++ and -- are not inc/dec operators on non-variables, they are + + and - - sequences
2(  echo $(( --7 ))   )
3(  echo $(( ++7 ))   )
4(  echo $(( -- 7 ))  )
5(  echo $(( ++ 7 ))  )
6
7#ash# ((++array[0] ))
8#ash# echo 1 $array
9#ash# (( ++ array[0] ))
10#ash# echo 2 $array
11
12#ash# (( ++a ))
13#ash# echo 1 $a
14#ash# (( ++ a ))
15#ash# echo 2 $a
16
17#ash# (( --a ))
18#ash# echo 1 $a
19#ash# (( -- a ))
20#ash# echo 0 $a
21      a=0
22
23echo 5 $(( 4 + ++a ))
24echo 1 $a
25
26# this is treated as 4 + ++a
27echo 6 $(( 4+++a ))
28echo 2 $a
29      a=2
30
31# this is treated as 4 - --a
32echo 3 $(( 4---a ))
33echo 1 $a
34      a=1
35
36echo 4 $(( 4 - -- a ))
37echo 0 $a
38
39#ash# (( -- ))
40# -- is not a dec operator on non-variable, it is the - - sequence
41echo $(( ---7 ))
42(  echo $(( -- - 7 ))  )
43
44#ash# (( ++ ))
45# ++ is not a inc operator on non-variable, it is the + + sequence
46echo $(( ++7 ))
47(  echo $(( ++ + 7 ))  )
48
49echo -7 $(( ++-7 ))
50echo -7 $(( ++ - 7 ))
51
52echo 7 $(( +--7 ))
53echo 7 $(( -- + 7 ))
54