zsh: check if string is in array

Question

E.g.

foo=(a b c) 

Now, how can I do an easy check if b is in $foo?

Answer 1

You can use reverse subscripting:

pax$ foo=(a b c)  pax$ if [[ ${foo[(r)b]} == b ]] ; then ; echo yes ; else ; echo no ; fi yes  pax$ if [[ ${foo[(r)x]} == x ]] ; then ; echo yes ; else ; echo no ; fi no 

You'll find the datails under man zshparam under Subscript Flags (at least in zsh 4.3.10 under Ubuntu 10.10).

---

Alternatively (thanks to geekosaur for this), you can use:

pax$ if [[ ${foo[(i)b]} -le ${#foo} ]] ; then ; echo yes ; else ; echo no ; fi 

You can see what you get out of those two expressions by simply doing:

pax$ echo ${foo[(i)a]} ${#foo} 1 3  pax$ echo ${foo[(i)b]} ${#foo} 2 3  pax$ echo ${foo[(i)c]} ${#foo} 3 3  pax$ echo ${foo[(i)d]} ${#foo} 4 3 

Answer 2

(( ${foo[(I)b]} )) \   && echo "it's in" \   || echo "it's somewhere else maybe"