Automatic file and folder naming - fortran

Question

I am a new Fortran user. I am trying to create a file name according to date and time. I only know the command for opening fie which is:
open (unit=10,file='test.txt')
I want to have a file name instead of 'test.txt' using the current date and time when program execute. If anyone can help me I will be grateful then.

Answer 1

You can use date_and_time to achieve this:
module time_ftcs
contains
function timestamp() result(str)
implicit none
character(len=20) :: str
integer :: values(8)
character(len=4) :: year
character(len=2) :: month
character(len=2) :: day, hour, minute, second
character(len=5) :: zone
! Get current time
call date_and_time(VALUES=values, ZONE=zone)
write(year,'(i4.4)') values(1)
write(month,'(i2.2)') values(2)
write(day,'(i2.2)') values(3)
write(hour,'(i2.2)') values(5)
write(minute,'(i2.2)') values(6)
write(second,'(i2.2)') values(7)
str = year//'-'//month//'-'//day//'_'&
//hour//':'//minute//':'//second
end function timestamp
end module
program test
use time_ftcs, only: timestamp
open (unit=10,file='test'//trim(timestamp())//'.txt')
write(10,*) 'Hello World'
close(10)
end program
This results in a file
$cat test2015-04-05_09:32:27.txt
Hello World

Answer 2

You can use the intrinsic subroutine date_and_time to achieve this:
module time_ftcs
contains
function timestamp() result(str)
implicit none
character(len=15) :: str
character(len=8) :: dt
character(len=10) :: tm
! Get current time
call date_and_time(DATE=dt, TIME=tm)
str = dt//'_'//tm(1:6) ! tm(7:10) are milliseconds and decimal point
end function timestamp
end module
program test
use time_ftcs, only: timestamp
open (unit=10,file='test_'//timestamp//'.txt')
write(10,*) 'Hello World'
close(10)
end program
This should result in a file
$cat test_20150405_093227.txt
Hello World