this batch script generate a password include at least 1 upper letter, 1 lower letter, 1 numeric

gen_pwd.bat

:: to generate a 10 length password use below in .bat
:: call gen_pwd.bat 10

@echo off
setlocal enableextensions enabledelayedexpansion
set "lower=abcdefghijklmnopqrstuvwxyz"
set "upper=ABCDEFGHIJKLMNOPQRSTUVWXYZ"
set "numeric=0123456789"
set "alphanumeric=%lower%%upper%%numeric%"

set "pwdLength=%1"

set /a part1=1
set /a part2=%part1%+1
set /a part3=%pwdLength%-%part2%

set "result="

set /a index = 1
for /L %%i in (1,1,%pwdLength%) do (
    if !index!==1 (
        call :addUpper
    ) else if !index!==2 (
        call :addNumeric
    ) else if !index!==3 (
        call :addLower
    ) else (
        call :addAny
    )
    set /a index+=1
)

@echo %result%
endlocal
goto :eof

:addUpper
set /a u=%random% %% 25 + 1
set result=%result%!upper:~%u%,1!
goto :eof

:addLower
set /a u=%random% %% 25 + 1
set result=%result%!lower:~%u%,1!
goto :eof

:addNumeric
set /a n=%random% %% 9 + 1
set result=%result%!numeric:~%n%,1!
goto :eof

:addAny
set /a s=%random% %% 61 + 1
set result=%result%!alphanumeric:~%s%,1!
goto :eof

:: Batch file: random alphanumeric sequence
:: https://stackoverflow.com/questions/46573603/batch-file-random-alphanumeric-sequence