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| | == Conditional Operators == | | == Conditional Operators == |
| | {| class="ts" | | {| class="ts" |
| − | |- | + | |- |
| − | | if || else || elseif || end | + | | if |- | else |- | elseif |- | end |
| | |} | | |} |
| | | | |
Revision as of 22:02, 2 November 2018
Lua operators are expressions used to perform calculations or to pass arguments between different value types.
Conditional Operators
| - | else |- | elseif |- | end
|
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
|
|
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
|
|
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 |
|
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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