(i) LUA basic syntax

1. Starting from Hellowrold

1 -- syntax is similar to Python, and you can use print directly like Python 2 -- Here I can write the Chinese directly, which is obviously regarded as a comment. In Lua, two-represents a comment 3--[[4     This form can represent a multiline comment 5]]6  7-- in Lua, a semicolon can be appended to a statement, but it can also be added without.  8print("helloWorld")

basic types of 2.lua

1 --Lua, like Python, does not need to declare a variable like C because it has a type of value2 --assign values directly to variables3 4 --[[5 the basic types of LUA are: nil (empty)6 Boolean (Boolean)7 number (numeric)8 String (String)9 Table (Tables)Ten function, and so on . One  A ]] -  - --[[ the Note: When assigning a value, you can write multiple statements in a single line, separated by a space or;  - This is just a demo, but it's not recommended in real-world development . - ]] -A =123; b="Satori"; c=3.14;d =Math.PI + --to view the type of a value using type - Print(type(a),type(b),type(c),type(d))--Number string number number + --As you can see, there is no int float in Lua and so on, as long as it is a number, type all A Print(type(Print))--function at  - --If a variable we are not assigned to use directly, in Python will be an error, prompting the name XXX is not defined - --However, there is no error in Lua, and for an unassigned variable, the default is nil in Lua . - --Nil is used to differentiate other variables, assigning a global variable to nil equals deleting the global variable - Print(MMP,type(MMP))--Nil Nil -  in --in Lua, only false and nil represent false, and others are true. 0 and empty strings are true in Lua, which is not the same as Python -  to --in Lua, once a string has been created, it cannot be modified. This is the same as Python, but you can use replace to modify and return a new string in Python + --then Lua has a similar approach, and the method also gets a return value that does not modify the original value -S1 ="Hello cruel world" theS2 =string.gsub(S1,"Cruel","beautiful") * Print(S1)--Hello cruel world $ Print(S2)--Hello beautiful WorldPanax Notoginseng  - --and in Lua, you can use single quotes or double quotes the --similar to Python, if the input string itself has single quotes, then the outer is double-quoted, and vice versa + Print("I ' m Satori")--I ' m Satori A --if I have to use the same quotation marks, you can use the escape character to escape the inner quotation marks . the Print('i\ ' m Satori')--I ' m Satori +  - --[[ $ some escape characters $ \a: Bell - \b: Backspace - \f: Provide form the \ n: Line break - \ r: EnterWuyi \ t: watchmaking]] the Print("I am \ r Satori, come from \ n Oriental Spiritual Temple") - --[[ Wu Satori, come from - Oriental Spiritual Temple]] About  $ --The string can also be represented using \ plus a three-digit number, which is the corresponding ASCII table - Print("\065")--A -  - --If you want to express multiple lines of string, you can use [[]], similar to the three quotes in Python "" AS3 =[[ + The village Lori cheated me old and powerless the often happen with me sex - Relationship $ ]] the Print(S3) the --[[ the The village Lori cheated me old and powerless the often happen with me sex - Relationship in ]] the  the --if a string and a number are calculated, then the string is tried to be converted into a number. About --obviously the string must be made up of numbers, and if it contains a character that is not a number, it will be an error and cannot be converted the Print("666"+1)--667 the  the --string connection, in Lua: Represents a string connection + --It is not possible to use the form "a" + "B", which is allowed in Python, but not in Lua. But you can use: -S4 ="Satori" the Print("a".."b".. S4)--AB SatoriBayi Print("1".."+".."1".." == ".."2")--+ = 2 the  the --What if I want to get the length of a string? Use the Len function in Python, but use # in Lua.  - --and # in Python notation, so the two languages are similar in some places, some are completely different, it's really interesting - Print(#"I casually write the standard 15 words")-- $ the --The output is 45, eh, not 15? I must have found the answer at one glance, a kanji account of three bytes the --and Lua is using UTF-8 encoding by default. It is worth mentioning that the results of using the Len function in Python are calculated as the --because in Python, Len calculates the number of characters, not the number of bytes.  the --and in the go language, the result of the calculation is also 45, which is also a byte. If you want the number of characters, you need to convert []rune] in go.  -S6 ="MMP" the Print(#s6)--3 the  the --There is also a type called table in Lua, which is a dictionary (hash table) in Python, and key and value one by one correspond94Hash_map = {} thehash_map["Satori"] ="Oriental Spiritual Temple" the Print(hash_map["Satori"])--Oriental Spiritual Temple the --assigns a hash_map to another variable and deletes the Hash_map98Hash_map_1 =Hash_map AboutHash_map =Nil - Print(HASH_MAP)--Nil101 Print(hash_map_1["Satori"])--Oriental Spiritual Temple102 --you can see that even if hash_map is removed, it does not affect HASH_MAP1103 --Lua garbage collection is similar to the reference count in Python, and when HASH_MAP1 is also assigned nil, the garbage resource is deleted when no variable is referenced.104 --If you access a non-existent key, you get nil . thex = {}106x[1] =2107x[2] =3108 Print(x[1], x[2], x[3])--2 3 Nil109 --to remove an element from a table, assign a value of nil directly thex[1] =Nil111 Print(x[1])--Nil the --and table This structure, you can also use. To access113X.name ="Satori" the Print(X.name)--Satori

(i) LUA basic syntax