Check if index value exists

[Drakath]

Is there a way to check if a specific index value in a table exists?

For example I have two tables:

table = {{1,2},{1}}

Script selects a random table.

How can I check if table[randomTable][2] exists?

[Dealman]

Well, if it doesn't exist - it should return nil.

[Drakath]

Well, if it doesn't exist - it should return nil.

I did try those:

if table[2][2] then 
if table[2][2]~=nil then 

but in both cases it's: ERROR: attempt to index field '?' (a nil value)

[Dealman]

Well, because that value evidently doesn't exist. Hence, it returns nil.

If you'd have done it like this instead;

table[1][2] 

Then it would return 2.

table[2][1] 

Would return the last value, 1.

[novo]

(Just seen Dealman's latter reply but still going to publish this as an additional information).

As Dealman stated above, in case an index does not contain anything it returns nil. Which entails an error when indexing a nil value.

  
local table = 
{ 
    {"A", "B"} 
    {"A"} 
} 
if table[2] then 
    print(tostring(table[2][2])) -- tostring in order to be able to print any kind of variable 
    print(tostring(nil)) -- prints nil 
end 
if table[3] then -- does not exist, hence not following up 
end 
  

[Drakath]

I do know it's a nil but how can a script check if table[2][2] doesn't exist?

[novo]

  
not table[2][2] -- not + nil = true / false + false = true / negative + negative = positive (mathematical reference) 
  

So you can basically go through an if statement, or any other way you prefer, using the above trick to check whether that table value is either nil or false - as I did with table[3] within my previous sample code.

[Drakath]

  
not table[2][2] -- not + nil = true / false + false = true / negative + negative = positive (mathematical reference) 
  

So you can basically go through an if statement, or any other way you prefer, using the above trick to check whether that table value is either nil or false - as I did with table[3] within my previous sample code.

What if table[randomIndex][2] can be either nil or true?

  
local isTrue = not table[randomIndex][2] --if true it will convert to false 
if not isTrue then --if not false = true? 
  

Is that how it works?

[Mr_Moose]

Check the index at each level, everything that has a value is true while false and nil (no value) means false in below if statement.

if not table or not table[randomIndex] or not table[randomIndex][2] then return end 

[Drakath]

Thank you all for helping. It is solved.