Quick Concatenation Question For Unpacking?
So I found that .. and , can work for concatenating for example,
print("hello" .. " my dude")
OR
print("hello", " my dude")
however, that's not my main question. vvvvv
code = {5455, 45, 23, 65, 89, 21, 45}
print("this code ; " .. unpack(code))
this only prints the first number of the table, 5455
WHILE
code = {5455, 45, 23, 65, 89, 21, 45}
print("this code ; ", unpack(code))
this print ALL of the numbers of the table. I don't understand. Can someone explain the logic behind this? I am confused and it will help me understand things better in the future.
1 answer
unpack turns a table into a tuple. Tuples can be used in three places in Lua:
(The end of) an assignment:
local t = {1, 2}
local a, b = unpack(t)
-- same as a, b = 1, 2
(The last part of ) function calls:
local t = {1, 2}
print(unpack(t))
-- same as print(1, 2)
and (the last element in) table literals:
local t = {1, 2}
local u = {3, unpack(t)}
-- same as u = {3, 1, 2}
If you use a tuple anywhere else, such as with an operator like + or .., it will only use the first value in the tuple:
local t = {1, 2}
local a = 3 * unpack(t)
-- same as a = 3 * 1
Parenthesis also take only the first value in a tuple:
local t = {1, 2}
print( (unpack(t)) )
-- same as print(1)
In your case, it's the .. which eliminates the remainder of the tuple after the first one.
print isn't really a way to "concatenate" strings, it's just something it happens to do if you give it multiple things.
You can use table.concat(list, " ") to concatenate the elements of list, separating them by spaces. (Note that this requires the elements of list be properly strings / numbers; unlike print, tostring will not be automatically called for other types of objects).
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