如何用Fortran批量生成文件

设要生成4000个文件，文件名为AA1-AA4000，如何写循环生成文件,而不用写4000次write命令呢?用内部文件：

示例代码：

program main

implicit none​

character(len=80) :: filename,form

integer :: i

do i=1,4000

select case (i)

case (1:9)

write(form,’(i1)’) i

case (10:99)

write(form,’(i2)’) i

case (100:999)

write(form,’(i3)’) i

case (1000:9999)

write(form,’(i4)’) i

end select

write(filename,*) “AA”,trim(form),".TXT"

open(10,file=filename)

write(10,*) i

close(10)

end do

stop

end