How to check if argument is empty?

[Hugo_Almeidowski]

I can't find anything on Google.

So, I made this command called /criarped that has three arguments.

If I don't put all the three arguments, it returns an error

I want it that if I don't put let's say the third argument, it will just get my dimension. (I can do this) I just don't know how to check if the argument is empty

[IIYAMA]

arg1, arg2, ...: Each word after command name in the original command is passed here in a seperate variable. If there is no value for an argument, its variable will contain nil. You can deal with a variable number of arguments using the vararg expression, as shown in Server Example 2 below.

https://wiki.multitheftauto.com/wiki/AddCommandHandler

 

if argument then -- check
  
end

 

@Hugo_Almeidowski

 

[Hugo_Almeidowski]

5 minutes ago, IIYAMA said:

arg1, arg2, ...: Each word after command name in the original command is passed here in a seperate variable. If there is no value for an argument, its variable will contain nil. You can deal with a variable number of arguments using the vararg expression, as shown in Server Example 2 below.

https://wiki.multitheftauto.com/wiki/AddCommandHandler

 

if argument then -- check
  
end

 

@Hugo_Almeidowski

 

So, if argument = nil then

 

end

 

Right?

Thanks!

[Sorata_Kanda]

45 minutes ago, Hugo_Almeidowski said:

So, if argument = nil then

 

end

 

Right?

Thanks!

if argument then
  
end

represents

if argument ~= nil then
  
end

 

If you'd like to check if it's nil:

if not argument then
  -- Do something
end

-- or

if argument == nil then
  -- Do something
end

 

EDIT: It doesn't matter which of the two methods you choose. As far as I know, the common code style uses

if not element then
  -- Do something
end
-- etc.

 

Edited January 29, 2019 by Sorata_Kanda

[Zorgman]

if not argument then
  -- Do something
end

^ This could also mean that argument == false. Irrelevant difference for OP's specific use case, but still

[Hugo_Almeidowski]

8 minutes ago, Sorata_Kanda said:

if argument then
  
end

represents

if argument ~= nil then
  
end

 

If you'd like to check if it's nil:

if not argument then
  -- Do something
end

-- or

if argument == nil then
  -- Do something
end

 

EDIT: It doesn't matter which of the two methods you choose. As far as I know, the common code style uses

if not element then
  -- Do something
end
-- etc.

 

But for what I've been coding it seems that

if argument then



end

means that if argument == true (is valid) then

so what if I want to check if the argument is valid?

[Zorgman]

9 minutes ago, Hugo_Almeidowski said:

But for what I've been coding it seems that

if argument then



end

means that if argument == true (is valid) then

so what if I want to check if the argument is valid? 

It means that argument has a value assigned and that the value is different from false.

What you are looking for is:

if not argument or type(argument)~= "number" then
  argument = getPlayerDimension(player)
end

 

Edited January 29, 2019 by Zorgman

[Hugo_Almeidowski]

6 minutes ago, Zorgman said:

It means that argument has a value assigned and that the value is different from false.

What you are looking for is:

if not argument or type(argument)~= "number" then
  argument = getPlayerDimension(player)
end

 

I've done it like this

if argument and argument2 and argument3 then
  
else if argument and argument2 then
    
else if argument then
      
else
      
end

 

[Mr.Loki]

Another simpler way is creating a ternary operator.
For example:

argument3 = tonumber(argument3) and argument3 or getElementDimension(player)
  -- what this does is if arg3 is a number use it else it sets arg3 as the player's dimension

no need for else, if etc...

[thisdp]

addCommandHandler("test",function(player,command,...)
    local args = {...}
    print(#args) --How many arguments are passed
end)