Lua basic grammar

lua Variables default to global variables , add to local Then it's a local variable
Variables that are not declared are nil

The symbol connecting strings is the connection of two dots

Type conversion , The length of the string is #+ Variable name

function

Array

_G Table that is a global variable

~= Means not equal to

True and false if

loop

Ipairs continuity pairs No continuous , It can be iterated out completely