Lua introductory case of actual combat 1234 custom function and the standard library function

– Example – Functions.
Function-related case customization

定义函数1-简单调用

– Define a function without parameters or return value.

案例如下

function myFirstLuaFunction()
    print("My first lua function was called")
end

– Call myFirstLuaFunction.

myFirstLuaFunction()

-------- Output ------

My first lua function was called

定义函数2-带返回值

– Example – More functions.

– Define a function with a return value.

function mySecondLuaFunction()
    return "string from my second function"
end

– Call function returning a value.

a=mySecondLuaFunction("string")
print(a)

-------- Output ------

string from my second function

定义函数3-多参数返回

– Define function with multiple parameters and multiple return values.

function myFirstLuaFunctionWithMultipleReturnValues(a,b,c)
    return a,b,c,"My first lua function with multiple return values", 1, true
end

a,b,c,d,e,f = myFirstLuaFunctionWithMultipleReturnValues(1,2,"three")
print(a,b,c,d,e,f)

-------- Output ------

1       2       three   My first lua function with multiple return values       1       true

定义函数4-全局变量与局部变量

– All variables are global in scope by default.

b=“global”

– To make local variables you must put the keyword ‘local’ in front.

function myfunc()
    local b=" local variable"
    a="global variable"
    print(a,b)
end

调用函数

myfunc()
print(a,b)

-------- Output ------

global variable local variable
global variable global

定义函数5-格式化输出

function printf(fmt, ...)
    io.write(string.format(fmt, ...))
end

printf("Hello %s from %s on %s\n",
       os.getenv"USER" or "there", _VERSION, os.date())

-------- Output ------

Hello there from Lua 5.1 on 07/30/22 14:34:25

Define comments on multiple lines

-- Example 31   --[[

 Standard Libraries

  Lua has standard built-in libraries for common operations in
  math, string, table, input/output & operating system facilities.

 External Libraries

  Numerous other libraries have been created: sockets, XML, profiling,
  logging, unittests, GUI toolkits, web frameworks, and many more.

]]

-------- Output ------

标准函数库

标准数学库

– Math functions:
– math.abs, math.acos, math.asin, math.atan, math.atan2,
– math.ceil, math.cos, math.cosh, math.deg, math.exp, math.floor,
– math.fmod, math.frexp, math.huge, math.ldexp, math.log, math.log10,
– math.max, math.min, math.modf, math.pi, math.pow, math.rad,
– math.random, math.randomseed, math.sin, math.sinh, math.sqrt,
– math.tan, math.tanh

print(math.sqrt(9), math.pi)


-------- Output ------

3       3.1415926535898

标准库string

– String functions:
– string.byte, string.char, string.dump, string.find, string.format,
– string.gfind, string.gsub, string.len, string.lower, string.match,
– string.rep, string.reverse, string.sub, string.upper

print(string.upper("lower"),string.rep("a",5),string.find("abcde", "cd"))


-------- Output ------

LOWER   aaaaa   3       4

标准库table

– Table functions:
– table.concat, table.insert, table.maxn, table.remove, table.sort

a={2}
table.insert(a,3);
table.insert(a,4);
table.sort(a,function(v1,v2) return v1 > v2 end)
for i,v in ipairs(a) do print(i,v) end

-------- Output ------

1 4
2 3
3 2

标准输入输出IO

– IO functions:
– io.close , io.flush, io.input, io.lines, io.open, io.output, io.popen,
– io.read, io.stderr, io.stdin, io.stdout, io.tmpfile, io.type, io.write,
– file:close, file:flush, file:lines ,file:read,
– file:seek, file:setvbuf, file:write

   print(io.open("file doesn't exist", "r"))

-------- Output ------

nil file doesn’t exist: No such file or directory 2

System function configurationOS库

– OS functions:
– os.clock, os.date, os.difftime, os.execute, os.exit, os.getenv,
– os.remove, os.rename, os.setlocale, os.time, os.tmpname

print(os.date())

-------- Output ------

07/30/22 14:39:54

扩展库支持

– Lua has support for external modules using the ‘require’ function
– INFO: A dialog will popup but it could get hidden behind the console.

require( "iuplua" )
ml = iup.multiline
    {
    expand="YES",
    value="Quit this multiline edit app to continue Tutorial!",
    border="YES"
    }
dlg = iup.dialog{ml; title="IupMultiline", size="QUARTERxQUARTER",}
dlg:show()
print("Exit GUI app to continue!")
iup.MainLoop()

-------- Output ------

failed to load & run sample code

Configuration is not over yet.

```css
-- Example 38   --[[

 To learn more about Lua scripting see

 Lua Tutorials: http://lua-users.org/wiki/TutorialDirectory

 "Programming in Lua" Book: http://www.inf.puc-rio.br/~roberto/pil2/

 Lua 5.1 Reference Manual:
     Start/Programs/Lua/Documentation/Lua 5.1 Reference Manual

 Examples: Start/Programs/Lua/Examples
]]

-------- Output ------


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