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Lua Cheat Sheet
-- Lua Cheat Sheet for Programmers, by Al Sweigart http://coffeeghost.net
-- This cheat sheet is an executable Lua program.
--[[ This is
a multline comment]]
---[[ This is a neat trick. The first -- makes -[[ not a multiline comment.
print("This line executes.")
--]] The rest of this line is also a comment.
print("Here is a string" .. ' concatenated with ' .. 2 .. ' other strings.')
-- Note: All number types are doubles. There're no integers.
print(type(42), type(42.0)) -- prints out "number number"
variable_one = 1 + 2 - 3 -- This will equal zero.
variable_One = "Variables are case sensitive."
negative_twofiftysix = -2^8
a, b = 42, 101 --mulitple assignment
a, b = b, a --provides a nice value swap trick
x, y, z = 1, 2, 3, "this value is discarded"
print(previously_unused_variable == nil) -- prints true, all vars start as nil
print(nil == 0 or nil == "") -- prints false, nil is not the same as false or 0
print('The # len operator says there are ' .. #'hello' .. ' letters in "hello".')
some_bool_variable = true and false or true and not false
a_table = {['spam'] = "Type something in:", ['eggs'] = 10} -- tables are dictionaries/arrays
print(a_table['spam'])
what_the_user_typed_in = io.read()
print('You typed in ' .. what_the_user_typed_in)
if 10 < 20 then
print( "apple" == "orange" ) -- prints false
print( "apple" ~= "orange" ) -- true, an apple is not equal to an orange
local foo
foo = 42
print(foo)
elseif 50 < 100 then
--These clauses can contain no lines of code.
end
print(foo) -- prints nil, local foo exists only in that "if" block above
m = 0
while m < 10 do
print("howdy " .. m)
m = m + 1 -- there is no m++ or m += 1
repeat
print("Repeat loops check the condition at end, and stops if it is true.")
break -- breaks out of the loop early
until m == 9999
end
for i = 1, 10 do
for j = 1, 10, 2 do
print("for loops add 1 to i and 2 to j each iteration " .. i .. ' ' .. j)
end
end
function Greet(name)
print('Hello ' .. name)
bar = 100
return "returns nil if you don't have a return statement."
end
Greet('Al Sweigart')
print(bar) -- prints 100
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