[BASH] Arrays and dynamic variable

[tompl]

Hello,
I need help with dynamic variable which get number and string from array.

_0_USERS=(11 taaa 15 20 22)
grupa=0
for ((n=0; n<3;n=$[n+1]));do
echo "
$[_${grupa}_USERS[$n]]
_${grupa}_USERS[$n]"
done

Resault is:

11
_0_USERS[0]

0
_0_USERS[1]

15
_0_USERS[2]

As you can see, everything is ok until it meet a string than it put 0 instead "taaa". If i put only strings into array still get 0s

[likwid]

$[_${grupa}_USERS[$n]]

For some reason, that can't be evaluated into a string. I've never used brackets like this, so I am not too sure why. Honestly, this code is awful looking, and you should re think the way you're doing things. What exactly are you trying to accomplish?

[Cabhan]

I agree with likwid that this script is very poor-looking. It can probably be written better.

In any event, the problem here is that $[...] notation invokes arithmetic mode. Strings become 0 in arithmetic mode, hence the 0. What you actually want is something like:

${_0_$grupa_USERS[$n]}

(that is, ${...} syntax instead).

[tompl]

I agree with likwid that this script is very poor-looking. It can probably be written better.

In any event, the problem here is that $[...] notation invokes arithmetic mode. Strings become 0 in arithmetic mode, hence the 0. What you actually want is something like:

${_0_$grupa_USERS[$n]}

(that is, ${...} syntax instead).

./a: line 4: ${_0_$grupa_USERS[$n]}: bad substitution

_0_USERS=(11 u 15 20 22)
grupa=0
for ((n=0; n<3;n=$[n+1]));do
echo ${_0_$grupa_USERS[$n]}
done

This is only an example of problem. I dont care about "looking", i just want it to work. Now i had to refer to another array with names and that works

[vsemaska]

You need to use the eval command:

eval echo \${_${grupa}_USERS[$n]}

Vic

[likwid]

You will care about how it looks when you go back in a year to add/tweak some code.

I suggest thinking about the problem to see if you can avoid this situation. There are lots of roads to the same point, some shorter, and less windy than others.

[tompl]

You will care about how it looks when you go back in a year to add/tweak some code.

I suggest thinking about the problem to see if you can avoid this situation. There are lots of roads to the same point, some shorter, and less windy than others.

I wont use it in my code, a just need a solution to my problem... im not a programmer, i just writting for my self to use it in my network to change transfers.

You need to use the eval command:

eval echo \${_${grupa}_USERS[$n]}

Vic

THX it works !!