Difference between revisions of "Basic Lua: Operators"

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(Created page with "Lua operators are expressions used to perform calculations or to pass arguments between different value types. {| class="in" |- | class="i_arrow clickablecell" | Basic_Lua...")
 
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=== if ===
 
=== if ===
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if statements are one of the most common staples of programming, because programs & games & just about everything we do in life consists of if queries; should I wear this tie today? Do I need to go grocery shopping after work? Should I buy this game, or that game? etc. etc.
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! if condition is true (method 1) !!
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Let's start off with a basic condition based if query. Let's say that we have a variable called '''var''', which has a boolean value assigned to it, & that we want to check what said boolean value is.
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<syntaxhighlight lang="lua">
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local a = true
 
local a = true
  
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   print("a = true")
 
   print("a = true")
 
end
 
end
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</syntaxhighlight> || width="180px" | [[File:Basic_lua_(if_queries)_(1).png|frameless|center|180px]]
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Revision as of 21:19, 2 November 2018

Lua operators are expressions used to perform calculations or to pass arguments between different value types.

< Index >

Conditional Operators

if Query if something does or does not meet a certain condition.
else Do something else if the query condition was not met.
elseif Used to add additional if queries, if the initial query condition was not met.
end This is used to close various queries or functions; there must be the same amount of end as if; except in instances where elseif has been used.

if

if statements are one of the most common staples of programming, because programs & games & just about everything we do in life consists of if queries; should I wear this tie today? Do I need to go grocery shopping after work? Should I buy this game, or that game? etc. etc.

Let's start off with a basic condition based if query. Let's say that we have a variable called var, which has a boolean value assigned to it, & that we want to check what said boolean value is. 

local a = true

if a then
  print("a = true")
end
if condition is true (method 2) 
local a = true

if a == true then
  print("a = true")
end
Basic lua (if queries) (2).png
if condition is false 
local a = false

if a == false then
  print("a = false")
end
Basic lua (if queries) (3).png

else

if condition is not met, then do else 
local a = false

if a then
  print("a = true")
else
  print("a = false")
end
Basic lua (if queries) (4).png

elseif

if condition is not met, then do elseif 
local a = false

if a then
  print("a = true")
elseif a == false then
  print("a = false")
end
Basic lua (if queries) (5).png

Logical Operators

and Allows you to check multiple conditions in a single if query.
or Allows you to add an alternative if query into a single if query.
not Checks if condition equals false or negative.

and

if condition a is true and condition b is false then 
local a = true
local b = false

if a == true and b == false then
  print("a = true", "b = false")
end
Basic lua (if queries) (6).png

or

if condition is true or condition == true then 
local a = true

if a or a == true then
 print("a = true")
end
click to enlarge

not

if condition is not true 
local a = false

if not a then
 print("a = false")
end
click to enlarge

Comparison Operators

== Equal to.
~= Does not equal.
>= Greater than or equal to.
> Greater than.
<= Less than or equal to.
< Less than.

equal to

if a equals 1 
local a = 1

if a == 1 then
 print("a = 1")
end
click to enlarge

does not equal

if a does not equal 2 
local a = 1

if a ~= 2 then
 print("a = " .. a)
end
click to enlarge

greater than or equal to

if a is greater than or equal to 2 
local a = 5

if a >= 2 then
 print("a = " .. a)
end
click to enlarge

greater than

if a is greater than 2 
local a = 3

if a > 2 then
 print("a = " .. a)
end
click to enlarge

less than or equal to

if a less than or equal to 2 
local a = 2

if a <=  2 then
 print("a = " .. a)
end
click to enlarge

less than

if a less than 2 
local a = 0

if a <  2 then
 print("a = " .. a)
end
click to enlarge

Mathematical Operators

+ Add
- Subtract or invert
* Multiply
/ Divide
^ Power
% Remainder

add

1 + 2 = 3 
local a = 1
local b = 2
local result = a + b

print( result )
click to enlarge

subtract

3 - 2 = 1 
local a = 3
local b = 2
local result = a - b

print( result )
click to enlarge

inverse

inv of 3 = -3 
local a = 3
local result = -a

print( "original value: " .. a, "inversed value: " .. result )
click to enlarge

multiply

2 x 2 = 4 
local a = 2
local result = a * a

print( result )
click to enlarge

divide

10 ÷ 5 = 2 
local a = 10
local b = 5
local result = a / b

print( result )
click to enlarge

power

base of 2, power of 8 (2ⁿ) = 256 
local a, b = 2, 16
local result = a ^ b -- generate answer
 
-- break down power function into string result (ignore this code)
function power(i1, i2)
 local val = "" -- clear string
 --+--
 for i = 1, i2 do -- generate the longhand math formula
  if i < i2 then val = val..i1.."*" else val = val..i1 end
 end
 return "which is the equivalent of " .. val
end
 
print("power value of "..a.." & "..b.."  = " .. result, power(a,b))
click to enlarge

remainder

remainder of 25 ÷ 4 = 1 
local a = 25
local b = 4
local result = a / 4
local remainder = a % b
local decimal = remainder / b

print("result: 25 ÷ 4 = "  .. result, "remainder: .25 x 4 = " .. remainder, "decimal: 1 ÷ 4 = " .. decimal )
click to enlarge
< Index >

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