Cc3.2 + Lua (2) -- Lua basic syntax 1

[Nagging]

First, you have learned at least one host language (C ++, Java, etc.) by default, and then turn to Lua.

Because 51cto does not have code highlighting for Lua, I have to use it to make the Code look colorful. 650) This. width = 650; "src =" http://img.baidu.com/hi/face/ I _f32.gif "alt =" I _f32.gif "/>

This section only introduces the basic simple Syntax of Lua. For more instructions, see the Lua Chinese tutorial and Lua reference manual.

[Learning emotion]

> No extra points are required at the end of the statement;

> The statement block does not use braces {}, but the DO statement block end indicates the start and end of the statement block.

Braces {} represent a table structure.

> Operator ^: indicates a power operation. (2 ^ 10 = 1024)

> Not equal :~ =.

> Data type is not required for variable definition. Direct A = 10.

> And the return values of (and), or (OR) operations are not true/false. The variable value on the left or right of the operator.

> Except nil and false, all others are true. (0 and empty string "" are also true ).

> Variable values can be assigned together. (A, B, C = 10, 20, 30 ).

> The function can return multiple values. (Return a, B, c)

> In Lua, there is only one data structure type: Table ).

It can represent an array, a data structure, or a class.

> The subscript of the array starts from 1, instead of 0.

0. Lua environment Configuration

You can goLua Official WebsiteDownload the resource file from www.lua.org and write it in a text editor.

You can also useEclipse, DownloadLDT Plug-in to compile Lua code in eclipse.

0. Lua example

Let's take a look at a Lua example. The figure is fresh. 650) This. width = 650; "src =" http://img.baidu.com/hi/face/ I _f07.gif "alt =" I _f07.gif "/>

Note: The following code can be run directly. Yes. The main function is not required!

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/C1/wKiom1RE46ywaKPZAAKGP3sK2ew218.jpg "Title =" 11.png" alt = "wkiom1re46ywakpzaakgp3sk2ew218.jpg"/>

1. Data Type

> When defining a variable in Lua,No data type to write.

> Lua is defined as follows: a = 10; B = "Hello World ".

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/BA/wKioL1REiKywadAjAAJZDtvFBIo814.jpg "Title =" 1.png" alt = "wkiol1reikywadajaajzdtvfbio814.jpg"/>

2. Notes

(1) single line comment:--

(2) multi-line comment:-- [[--]

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BC/wKioL1REq5ODiclgAABMd1oJpmY804.jpg "Title =" 2.jpg" alt = "wkiol1req5odiclgaabmd1ojpmy804.jpg"/>

3. Output statement

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BC/wKioL1RErZqSoegcAAFyH41AcdA898.jpg "Title =" 3.jpg" alt = "wkiol1rerzqsoegcaafyh41acda898.jpg"/>

4. reserved keywords

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/BC/wKiom1REriSCpRN9AADAUcjLjjo203.jpg "Title =" 4.png" alt = "wkiom1reriscprn9aadaucjljjo203.jpg"/>

5. Operators

5.1 Arithmetic Operators

> Where^IsPower Operation.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BD/wKiom1REtADSqm0IAABnGBQARuI593.jpg "Title =" 11.jpg" alt = "wkiom1retadsqm0iaabngbqarui593.jpg"/>

5.2 Relational operators

> Where~ =IsNot equal.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BD/wKioL1REtFyw-BHpAACoyv31I_I769.jpg "Title =" 22.png" alt = "wKioL1REtFyw-BHpAACoyv31I_I769.jpg"/>

5.3 logical operators

> The logical operators in Lua do not return true/false, but A or B.

> The Three-object operator can be expressed as follows.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/BD/wKioL1REtGvCl6jDAADZm7_VAfA454.jpg "Title =" 33.png" alt = "wkiol1retgvcl6jdaadzm7_vafa454.jpg"/>

5.4 Concatenation Operators

>Two points ..String concatenation.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BD/wKioL1REtSKQCJQRAAA9vX1Ynjw599.jpg "Title =" 44.png" alt = "wkiol1retskqcjqraaa9vx1yn213599.jpg"/>

5.5 priority

> ^ And... are right links, and the rest are calculated from left to right.

> Priority: 650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BD/wKiom1REtRuTI3ChAACXlKBRKOM887.jpg "Title =" 55.png" alt = "wkiom1retruti3chaacxlkbrkom887.jpg"/>

6. Variable assignment and scope

(1) local variables (Local), Global variables.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BD/wKiom1REtbeQjnsCAACt9jyCERk129.jpg "Title =" a.jpg "alt =" wkiom1retbeqjnscaact9jycerk129.jpg "/>

(2) multi-value assignment

> The left side of the equal sign is the variable, and the right side is the assigned value. Values are assigned in sequence.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BE/wKiom1REvYbxFfm7AAGFXpOZZok917.jpg "Title =" I .png "alt =" wkiom1revybxffm7aagfxpozzok917.jpg "/>

7. Code Block

> UseDo end.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BD/wKiom1REti2jdARJAACmTkAAEks689.jpg "Title =" B .png "alt =" wkiom1reti2jdarjaacmtkaaeks689.jpg "/>

8. control statements

Table knowledge may be involved here, which will be introduced later.

 8.1 conditional statement if-else-then

>ElseifThere is no space in the middle.

> Don't forgetThen.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BE/wKioL1REt5vjSr9sAACm6F6bj3U023.jpg "Title =" q.png "alt =" wkiol1ret5vjsr9saacm6f6bj3u023.jpg "/>

 8.2 loop statement while-do

> The usage is similar to that in C ++.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BE/wKioL1REuFfwgS39AAB5EUP3OYg234.jpg "Title =" 20.png "alt =" wkiol1reuffwgs39aab5eup3oyg234.jpg "/>

 8.3 loop statement repeat-

> Similar to do-while in C ++.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BD/wKiom1REuRjyIg1GAABwKH4LbPY025.jpg "Title =" e.jpg "alt =" wkiom1reurjyig1gaabwkh4lbpy025.jpg "/>

 8.4. Loop statement for-do

The for loop statement is the most commonly used in Lua.

(1) usage 1: Number Traversal

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/BE/wKioL1REu26j_03tAAEdP9z276s735.jpg "Title =" r.png "alt =" wkiol1reu26j_03taaedp9z276s735.jpg "/>

(2)Usage 2: array Traversal

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BE/wKioL1REu32DwPOlAADi1wo40Uc298.jpg "Title =" rr.png "alt =" wkiol1reu32dwpolaadi1wo40uc298.jpg "/>

(3) usage 3: array traversal (ipairs)

> UseFor key, VAR in ipairs (t) Do end

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M02/4C/BE/wKioL1REvwLDLNYPAAFS6xs62PQ762.jpg "Title =" rrrr.png "alt =" wkiol1revwldlnypaafs6xs62pq762.jpg "/>

(4) usage 4: Table traversal (pairs)

> Traverse the entire table and output all the data in the table.

> UseFor key, VAR in pairs (t) Do end

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/BF/wKioL1REv7-CYI5kAAC9jO5UOsI389.jpg "Title =" rrrrr.png "alt =" wKioL1REv7-CYI5kAAC9jO5UOsI389.jpg "/>

(5) differences between ipairs and Pairs

>Ipairs: Mainly used for table array traversal, that is, the table subscript is a positive integer, and from 1 ~ N consecutive.

>Pairs: Used to traverse the entire table.

9. Function

The function is defined as follows:

Function Name (parameter list) Statement block end

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/BF/wKioL1REwaaSSiI2AABlx762WZ4675.jpg "Title =" z.png "alt =" wkiol1rewaassii2aablx762wz4675.jpg "/>

 9.1 variable parameters

At the end of the function parameter list, useThree points ...The input parameter is variable.

Variable parameters are stored in an array of tables.ARG.

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BE/wKiom1REwnbw-gF3AAE6OCcm7bQ161.jpg "Title =" zz.png "alt =" wKiom1REwnbw-gF3AAE6OCcm7bQ161.jpg "/>

 9.2 multiple return values

The function can return multiple values.

Example:

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BF/wKioL1REw3nQbqqKAAHRKAlL0iQ038.jpg "Title =" zzz.jpg "alt =" wkiol1rew3nqbqqkaahrkall0iq038.jpg "/>

10. Table)

There is only one data structure in Lua: Table ).

Principle:Key-value pair.

 10.1 represents an array

Prerequisites:The subscript of the array is a positive integer and the value is continuously assigned.

And in Lua,Array subscript from1Start.(T [1], t [2], t [3]...)

Example:

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/C0/wKioL1REyTPB33zfAAI60I_FeIQ096.jpg "Title =" x.png "alt =" wkiol1reytpb33zfaai60i_feiq096.jpg "/>

 10.2 Table usage

(1) initialization assignment

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M01/4C/BF/wKiom1REzaWAsYJRAAHRvCnW2tI494.jpg "Title =" cc.png "alt =" wkiom1rezawasyjraahrvcnw2ti494.jpg "/>

(2) usage of table members

650) This. width = 650; "src =" http://s3.51cto.com/wyfs02/M00/4C/C0/wKioL1REztzR8hPSAACloajYwVE540.jpg "Title =" ccc.png "alt =" wkiol1reztzr8hpsaacloajywve540.jpg "/>

The basic syntax is finished. Please wait for the next decomposition...

This article is from the "summer wind" blog, please be sure to keep this source http://shahdza.blog.51cto.com/2410787/1565974

Cc3.2 + Lua (2) -- Lua basic syntax 1