Difference between revisions of "Basic lua: Tables"

Revision as of 01:03, 3 September 2022

Tables are one of the features of Lua script, that make the scripting language so dynamic & easy to use, as they allow us to easily create tables, insert, remove & sort data. Tables are often comprised of arrays that usually involve keywords - or an index number - & a value. Tables can be accessed using multiple different methods.

<

Index

>

Creating Tables

Below I am going to show you how to create various different types of tables/arrays.

Index Based Tables

method 1: automatically generated index values

local t = {1, 2, 3, 4, 5, "six", 7, "ate", 9} -- automatically assigns an index number to each value starting from 1
local str = "" -- empty string

for i = 1, #t do -- for 1 to table total, print value of index number
 str = str .. t[i] -- add current table index value to existing text data in the str variable
 if i < #t then str = str .. ", " end -- if i is less than table entry total then insert ", " into the str variable
end

print("table data: " .. str) -- print the table data
print( "table entry total: " .. #(t) ) -- print total of table entries

method 2: manually created index values

local t = {

[1] = 1,
[2] = "two",
[3] = 3,
[4] = 2 * 2,
[5] = "five",

}

local str = "" -- empty string

for i = 1, #t do -- for 1 to table total, print value of index number
 str = str .. t[i] -- add current table index value to existing text data in the str variable
 if i < #t then str = str .. ", " end -- if i is less than table entry total then insert ", " into the str variable
end

print("table data: " .. str) -- print the table data
print( "table entry total: " .. #(t) ) -- print total of table entries

Keyword Based Tables

keywords & values

local t = {

["hello world"] = "hello world",
example = "this also works",
camelCaseExample = "this will also work",
snake_case_example = "as will this"

}

for k, v in pairs(t) do
  print(k ..": " .. v)
end

print("\n...but as you can see it does not necessarily return them in the order they were created")

Index Values and Sub-Arrays

auto generated index entries with sub-arrays containing keywords
local t = { {x = 100, y = 300}, {x = 200, y = 111} } print("x = " .. t[1].x .. ", y = " .. t[1].y)

Keywords and Sub-Arrays

keyword tables with keyword sub-arrays containing keywords
local t_texts = { ["English"] = { {txt = "hello world!"}, {txt = "goodbye world!"} }, ["German"] = { {txt = "hallo welt!"}, {txt = "auf wiedersehen welt"} } } print( t_texts["English"][1].txt )

<