A quick note of LUA for later reference.

Lua is a powerful and intuitive general-purpose programming language developed in 1993 by a team of scrappy professors at Pontifical Catholic University of Rio de Janeiro, in Brazil.

Much of the inspiration for Lua came from the languages SOL (Simple Object Language) and DEL (data-entry language). In Portuguese, Sol means “sun” and Lua means “moon”.

Data Types

Basic Data Types

Data Types	Definition	Syntax	Example of Use
Number	A numeric value including positive values, negative values, and decimal values.	`10`, `3.5`, `-4`	To store how many followers you have on Instagram.
String	A sequence of individual characters inside quotations. It can be letters, spaces, numbers, or symbols.	`"This is a string"` `'I have 5 cats!'`	To store your username on a website.
Boolean (boo·lee·uhn)	A value that only has two possible values: true or false.	`true` `false`	To indicate whether you have dark mode on or not.
Nil	A representation for the absence of a value. If there is no value, it is nil.	`nil`	To indicate an empty box on a fillable form.

Note: There are also an additional four complex data types: Tables, Functions, Userdata, and Threads.

type(): get the data type of a variable.

Dynamic data type: Since variables in Lua do not have a type — it is just a container for data — you can reassign a value of any data type to a variable.

Type Convert

print("100" + 5)
--output: 105, "100" is first converted to number
print("100" + 5 .. 6)
--output:1056, 105 and 6 are converted to string

print("100" + 5)

--output: 105, "100" is first converted to number

print("100" + 5 .. 6)

--output:1056, 105 and 6 are converted to string

tostring() : converts a variable to string
tonumber(): converts a variable to number

Operations

Arithmetic Operators

Operator Name	Description	Syntax	Example	Result
Addition	Adds two numbers	x + y	5 + 2	7
Subtraction	Subtracts two numbers	x – y	5 – 2	3
Multiplication	Multiplies two numbers	x * y	5 * 2	10
Division	Divides two numbers	x / y	5 / 2	2.5
Exponential	Takes the exponent of two numbers	x ^ y	5 ^ 2	25
Remainder (also known as modulo or modulus)	Gives us the remaining leftover number after we’ve divided two numbers.	x % y	5 % 2	1
Negation	Reverses the sign value of the number.	-x	-(3+2)	-5

Logical Operators

Operator	Syntax	Description
`and`	`A and B`	`true` if values `A` and `B` are `true`, `false` otherwise.
`or`	`A or B`	`true` if at least one of `A` or `B` are `true`, `false` otherwise.
`not`	`not A`	`true` if `A` is `false` and `false` if `A` is `true`.

Order of Operations

The list below shows what operators are evaluated first from top to bottom:

^
not
*, /
+, -
<, >, <=, >=, ~=, ==
and
or

Like other programming language, LUA can use parentheses () to change the order of operations.

String Concatenation

concatenation operator (..).

print("Hello World, ".."LUA!")
--output: Hello World, LUA!

print("Hello World, ".."LUA!")

--output: Hello World, LUA!

Syntax

Comment

single line comment:

-- This is the comment line.

1 2	-- This is the comment line.

Code block comment:

--[[
This is the comment block.
]]

--[[

This is the comment block.

]]

Conditionals

If statement

If boolean_expression then
  -- do something
end

If boolean_expression then

-- do something

end

Comparison Operatoers, others are the same as Python or C/C++ except for: A ~= B: A doesn’t Equal B.

If-else statement

If boolean_experssion then
  -- do something
else
  -- do something else
end

If boolean_experssion then

-- do something

else

-- do something else

end

If-elseif statement

If boolean_experssion_1 then
  -- do something
elseif boolean_experssion_2 then
  -- do something else
else
  -- do something else
end

If boolean_experssion_1 then

-- do something

elseif boolean_experssion_2 then

-- do something else

else

-- do something else

end

Functions

Declare functions

Declare a function by using function keyword

-- A function that print Hello World!
function sayHello()
  print("Hello World!")
end -- end of the function

-- A function that print Hello World!

function sayHello()

print("Hello World!")

end -- end of the function

Declare a function with parameters and call the function with arguments (parameter is in the definition while argument is real value)

function sayHello(name) -- name is the parameter
  print("Hello World, "..name)
end

-- call the function
sayHello("LUA")  -- "LUA" is the argument

function sayHello(name) -- name is the parameter

print("Hello World, "..name)

end

-- call the function

sayHello("LUA") -- "LUA" is the argument

Declare a function with return

function sayHello(name)
  return ("Hello World, "..name)
end

function sayHello(name)

return ("Hello World, "..name)

end

Built-in functions

string.upper("hello") -- returns HELLO, more string functions https://www.codecademy.com/resources/docs/lua/strings
math.min(100, 250) -- returns 100
math.random() -- can return any decimal between 0 and 1
math.random(0, 100) -- can return any number between 0 and 100, including 0 or 100.

string.upper("hello") -- returns HELLO, more string functions https://www.codecademy.com/resources/docs/lua/strings

math.min(100, 250) -- returns 100

math.random() -- can return any decimal between 0 and 1

math.random(0, 100) -- can return any number between 0 and 100, including 0 or 100.

Run Lua on ubuntu terminal

Install LUA

sudo apt install lua5.3

1 2	sudo apt install lua5.3

Run LUA script

lua script.lua

1 2	lua script.lua

Some thoughs

LUA is quite similar to Python, I can get a baisc command of LUA with one hour because of the experience of Python programming. Although there're some small differences: 1, comment syntax; 2, not equal operator (~=); 3, type convert and string concatenation, 4, don't distinguish int and float; 5, no need to import built-in module, etc. Other than those small differences, I guess a Python programmer can easily have a good command of LUA within a short time, some Python codes are even able to directly run with LUA without any change.

Reference

LUA Getting started

Lua 5.4 Reference Manual

一	二	三	四	五	六	日
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9	10	11	12	13	14	15
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23	24	25	26	27	28	29
30

LUA Basics

Data Types

Basic Data Types

Type Convert

Operations

Arithmetic Operators

Logical Operators

Order of Operations

String Concatenation

Syntax

Comment

Conditionals

If statement

If-else statement

If-elseif statement

Functions

Declare functions

Built-in functions

Run Lua on ubuntu terminal

Install LUA

Run LUA script

Some thoughs

Reference

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Data Types

Basic Data Types

Type Convert

Operations

Arithmetic Operators

Logical Operators

Order of Operations

String Concatenation

Syntax

Comment

Conditionals

If statement

If-else statement

If-elseif statement

Functions

Declare functions

Built-in functions

Run Lua on ubuntu terminal

Install LUA

Run LUA script

Some thoughs

Reference

相关推荐

评论 抢沙发

热门标签

大家都在看

近期文章

分类目录

文章归档

最新评论

LinMao's Blog（林茂的博客）

觉得文章有用就打赏一下作者吧～

支付宝扫一扫打赏

微信扫一扫打赏

QQ联系我

回顶部

评论抢沙发