Best way to check whether [find] yields results?

RouterOS Scripting
1

Hi,

Because I can never remember how this works, I find myself using the following expressions interchangibly in order to determine whether one or more matching items exist:

    :if ([:len [/interface find name=$interfaceName]] > 0) do={
    :if ([/interface find name=$interfaceName] = "") do={
    :if [/interface find name=$interfaceName] do={

I would like to use the last option, but I don’t know whether it always works as expected, nor whether these are exactly equivalent.

Edit: Although I apparently can’t invert the last option easily, because I “cannot logically negate nothing”. Second option is just awkward. First option is a little long, but feels the most robust, as one would expect [find] to always return an array of results.

2

The correct method is only the first.

:if ([:len [/interface find where name="the name"]] > 0) do={} else={}

# or if used with print
:if ([:len [/interface print as-value where name="the name"]] > 0) do={} else={}

Stop.

Too often in scripts you get strange results when using an array and comparing it to simple strings:

:put ({} = "")
true

:put ([:toarray ""] = "")
true

Test for 3rd method:

:put ([:toarray ""] = true)
false

:put ({} = true)
false

:put ([:toarray "1,2,3,4"] = true)
false

:put ({1,2,3,4} = true)
false