I'm trying to run this command in batch file:
wmic nicconfig where macaddress=somemacaddr call SetDNSServerSearchOrder (an array paramter)
For example:
set dnslist[1]="172.12.3.1"
set dnslist[2]="222.123.2.1"
...
set dnslist[x]="135.132.1.2"
We don't know the dnslist size before running the batch.
How could we passing the dnslist to SetDNSServerSearchOrder directly?
There are no arrays in batch files, per se. What you have there is just a collection of environment variables with the same prefix. There's nothing special about that.
How to pass them to a command depends on the command (e.g. are they space-separated, i.e. individual arguments, or comma-separated, or something else entirely?). You need to create a string from those variables that matches the format the program expects, e.g. when they should be space-separated, create a string the following way:
setlocal enabledelayedexpansion
for /f "delims==" %%A in ('set dnslist[') do set List=!List! %%B
wmic nicconfig where macaddress=somemacaddr call SetDNSServerSearchOrder %List%
Likewise for different delimiters. Delayed expansion should ideally be enabled at the very start of your script; no use creating a new local environment in the middle of it, usually.
If you want to call the command once for every entry in your "list", you don't need to create the delimiter-separated list in the first place, but rather just call the command directly with the entry.