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| | == Conditional Operators == | | == Conditional Operators == |
| − | {| | + | {| class="ts" |
| | |- | | |- |
| | | if || else || elseif || end | | | if || else || elseif || end |
Revision as of 22:01, 2 November 2018
Lua operators are expressions used to perform calculations or to pass arguments between different value types.
Conditional Operators
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 say that we have a variable called var & we want to check if the var contains a boolean value of true...
local var = true
if var == true then
print("var = true")
end
| Quick note: if a variable contains a boolean value of true or false, then there is no need to use definitive query based operators as the variable on it's own will return the boolean value.
|
Now we want to perform the same query, but we want to check if the variable is false instead...
local var = true
if var == false then
print("var = false")
end
What do you think will happen when we run the code above? That's right, absolutely nothing will happen because var still contains the boolean value of true & we haven't told the program what to do if the variable doesn't return false, so let's do that now by using an else operator...
else
local var = true
if var == false then
print("var = false")
else
print("var = true")
end
Because the variable contains a boolean value of true, we skip the if var == false block of code & execute the line of code in the else section instead, which would print "var = true" to the log.
elseif
| if condition is not met, then do else |
|
local a = false
if a then
print("a = true")
else
print("a = false")
end
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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.
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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
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or
| if condition is true or condition == true then |
|
local a = true
if a or a == true then
print("a = true")
end |
|
not
| if condition is not true |
|
local a = false
if not a then
print("a = false")
end |
|
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 |
|
does not equal
| if a does not equal 2 |
|
local a = 1
if a ~= 2 then
print("a = " .. a)
end |
|
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 |
|
greater than
| if a is greater than 2 |
|
local a = 3
if a > 2 then
print("a = " .. a)
end |
|
less than or equal to
| if a less than or equal to 2 |
|
local a = 2
if a <= 2 then
print("a = " .. a)
end |
|
less than
| if a less than 2 |
|
local a = 0
if a < 2 then
print("a = " .. a)
end |
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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 ) |
|
subtract
| 3 - 2 = 1 |
|
local a = 3
local b = 2
local result = a - b
print( result ) |
|
inverse
| inv of 3 = -3 |
|
local a = 3
local result = -a
print( "original value: " .. a, "inversed value: " .. result ) |
|
multiply
| 2 x 2 = 4 |
|
local a = 2
local result = a * a
print( result ) |
|
divide
| 10 ÷ 5 = 2 |
|
local a = 10
local b = 5
local result = a / b
print( result ) |
|
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)) |
|
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 ) |
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