Boolean

< Scripting | Data Types

A Boolean, or Bool value, is a very simple data type. It is either a true or false value.

In Lua, when something is converted to a boolean, if the value is false or nil then it will be false, otherwise it is true.

Using Booleans

Booleans are most commonly used with conditional statements.

MyBool = true

if MyBool then
    --If "MyBool"'s value is true, this code is run.
else
    --If "MyBool"'s value is false, this code is run.
end

Converting booleans into strings

When converted to a string, booleans will return "true" or "false"

print(tostring(true))
print(tostring(false))

true

false

If you wanted it to print something other than true or false, you will have to use a conditional statements

local enabled = false

if enabled then
    print("Enabled")
else
    print("Disabled")
end

However, there is a cleaner way of doing this. You can use the following idiom:

print(enabled and "Enabled" or "Disabled")

and get the same results.

Operators

Not

The not operator returns true if the argument is false or nil, otherwise it will return false. The table below shows some example results

x	true	false	nil	"text"	0	1
not x	false	true	true	false	false	false

Example

One thing that the not operator is useful for is toggling something. To make a button toggle the visibility of a GUI, you can do:

button.MouseButton1Click:connect(function()
    frame.Visible = not frame.Visible
end)

And

The and operator returns the first argument if it is false or nil, otherwise it will return the second argument.

print(4 and 5)         --> 5
print(nil and 13)      --> nil
print(false and 13)    --> false

print(true and true) -- true
print(true and false) -- false
print(false and true) -- false
print(false and false) -- false

print(true and nil)
print(false and 5)
print({} and "hello")

nil false

hello

Or

Main article: or operator

The or operator returns the first argument if it is neither false nor nil, otherwise it will return the second argument.

print(true or true) -- true
print(true or false) -- true
print(false or true) -- true
print(false or false) -- false

print(4 or 5)          --> 4
print(false or 5)      --> 5

See also

• RBX.lua.BoolValue (Object)

• Programming in Lua 2.2: Booleans

• Lua Types Tutorial

• Or operator