@echo off
set /a a=1,b=2
set /a result=%a%+%b%
echo 加法运算：%a%+%b%=%result%
pause > nul 

@echo off

rem 减法
set /a a=24,b=4
set /a result=%a%-%b%

rem 乘法
set /a a=2,b=3
set /a result=%a%*%b%

rem 除法
set /a a=24,b=4
set /a result=%a%/%b%

pause > nul 

Function SelectFolder( myStartFolder )
	' Version: 0.1.0
	' Updated: 2021-08-07
	
    ' Standard housekeeping
    Dim objFolder, objItem, objShell
    
    ' Custom error handling
    On Error Resume Next
    SelectFolder = ""

    ' Create a dialog object
    Set objShell  = CreateObject( "Shell.Application" )
    Set objFolder = objShell.BrowseForFolder( 0, "Ñ¡ÔñÎļþ¼Ð", 0, myStartFolder )

    ' Return the path of the selected folder
    If IsObject( objfolder ) Then SelectFolder = objFolder.Self.Path

    ' Standard housekeeping
    Set objFolder = Nothing
    Set objshell  = Nothing
    On Error Goto 0
End Function

msgbox SelectFolder("C:\Windows\Desktop")

dim example
example="c:\windows\a.txt"

Function get_file_parts(in_file)
 ' Version: 0.1.0
 ' Updated: 2021-08-07
 
 dim input_path,input_filename, ext_name, left_part_name

 input_path=Left(in_file, InStrRev(in_file,"\") - 1)
 input_filename=Right(in_file,Len(in_file)-InStrRev(in_file,"\"))
 ' msgbox input_path
 ' msgbox input_filename
 left_part_name=Left(input_filename, InStrRev(input_filename,".") - 1)
 ext_name=Right(input_filename,Len(input_filename)-InStrRev(input_filename,".")+1)

 get_file_parts=input_path & "," & left_part_name & "," & ext_name

End Function

msgbox get_file_parts(example)
' c:\windows
' a
' .txt

@echo off

setlocal enabledelayedexpansion

for /f "tokens=*" %%i in (test.txt) do (
set /a h+=1 & set r!h!=%%i
)

set /a s=%random% %% h+1
echo !r%s%!
pause