How to get bash indexes of parameters array?

Question

I want indexes of parameters,

and can get it by dummy var:

dummy=( $@ )
echo ${!dummy[@]}

but is there straight way to get them, something like

$!@ ... not working
$!* ... not working

... or something like that?

NOTE: original function that i want to have without arr var is this:

function indexof()
{  search="$1"; shift; arr=( $@ ) 
   for i in "${!arr[@]}"; do [ "$search" == "${arr[$i]}" ] && return $i; done
   return -1
}

Solution 1

You can calculate from the number of arguments:

seq ${#@}

Solution 2

For the record, in zsh, the indexOf functionality is with:

$ set foo bar baz bar foo
$ echo $@[(i)bar] $@[(I)bar]
2 4

($2 is the first match (using the i subscript flag), $4 the last match (I subscript flag)).

Solution 3

You don't need a dummy array. You can use a counter variable:

indexof() {
    search="$1"; shift
    i=0
    for arg; do
        [ "$search" = "$arg" ] && return $i
        ((i++))
    done
    return -1
}

Note that for arg; do uses "$@" by default, that's why in "$@" can be omitted.

Comments

[dave_thompson_085]

Note that arr=( $@ ) will split args that contain IFS (by default whitespace); if you didn't dis-want this form entirely you would want arr=( "$@" )

[MetNP]

@dave_thompson_085 , yes, but this is first time that i see that parrametters array is not as other arrays (no syntax for getting indexes), or maybe indexes was meant for associative arrays initialy.

[MetNP]

nice, how to tell seq to go 0..n-1 instead 1..n like original code do

[Ipor Sircer]

it's very hard: seq 0 $((${#@}-1))

[Kusalananda]

$# would be better.