reading data from txt file in fortran

Question

I am writing a FORTRAN program that reads data from a text file and writing it to the console. the data file looks something like this

1234567890123456 12345         


        

Answer 1

List-directed IO (i.e., *) is easier, especially on input. Nevertheless, there are times to use full IO control so that is worth understanding. On input, the data items and descriptors must line up by column. For input, in Fw.d, the d doesn't matter if you have a decimal point in the data item. The fields must be wide enough on both input and output. There need to be enough descriptors, of types which match the variables and the data items. Compare to this example program:

program test_read

   implicit none
   integer, parameter :: VLI_K = selected_int_kind (18)
   integer, parameter :: DR_K = selected_real_kind (14)

   integer (VLI_K) :: i
   real (DR_K) :: a, b, c, d

   open (unit=15, file="data.txt", status='old',    &
             access='sequential', form='formatted', action='read' )

   read (15, 110)  i, a, b, c, d
   110 format (I16, 4(1X, F10.0) )
   write (*, 120) i, a, b, c, d
   120 format ( I18, 4 (2X, F12.3) )

   read (15, *) i, a, b, c, d
   write (*, 120) i, a, b, c, d

end program test_read