How to find the array length in unix shell?

Question

How to find the array length in unix shell?

Answer 1

Assuming bash:

~> declare -a foo
~> foo[0]="foo"
~> foo[1]="bar"
~> foo[2]="baz"
~> echo ${#foo[*]}
3

So, ${#ARRAY[*]} expands to the length of the array ARRAY.

Answer 2

$$ a=(1 2 3 4)
$$ echo ${#a[@]}
4