Empty array initialization

RouterOS Scripting
1

I want to use a global assoc array in my script for storing some host->ip pairs, and I’ve encountered a problem:
when I first time define variable, it has type = “nothing”, and can’t be used as an array.

I have to check it’s type and push some value to it, and then I can use a construct like

:global IP;
:if ([:typeof $IP] = "nothing") do={:set $IP {""};}

:set ($IP->$hostname) $ipaddress

It could be much easier to explicitely define type during init.

2

Try first to use right syntax:

:global IP; → :global IP value=;

:if ([:typeof $IP] = “nothing”) do={:set $IP {“”};} → :if ([:typeof $IP] = “nothing”) do={ :set $IP value={“”} }

And now think about possibilities:

:global newEmptyArray value={“”};

or

:global newEmptyArray value=[:toarray “”];

3

The second solution is the right one: [:toarray “”] is a zero length array.
{“”} is an array with one element which is a zero length string.

4

Also, one can use

({})

to have an empty array literal.

5

Thank you, man!

6

I found out incorrect work for syntax :local Array1 ({})
Works correctly :local Array1 [:toarray “”]

:global fArrayTest do={
# correct work :local Array1 [:toarray ""]
#  :local Array1 [:toarray ""]
# BUG, incorrect work :local Array1 ({})
  :local Array1 ({})
  :set ($Array1->([:len $Array1])) [:len $Array1]
  :put "len(Array1): $[:len $Array1]"
  :put "Array1:"
  :put $Array1
}

Test sequence for :local Array1 ({})

[admin@MikroTik] > $fArrayTest;
len(Array1): 1
Array1:
0
[admin@MikroTik] > $fArrayTest;
len(Array1): 2
Array1:
0;1
[admin@MikroTik] > $fArrayTest;
len(Array1): 3
Array1:
0;1;2

Test sequence for :local Array1 [:toarray “”]

[admin@MikroTik] > $fArrayTest;
len(Array1): 1
Array1:
0
[admin@MikroTik] > $fArrayTest;
len(Array1): 1
Array1:
0
[admin@MikroTik] > $fArrayTest;
len(Array1): 1
Array1:
0