I/O unit

[space-tech1]

Hello
I am new to fortran and I have aproblem in the i/o unit open() statement. The following code is part of a book example.For the input file in the example a ".dat" file named "filename.dat" is created and when prompted "what is the input file name" the "filename.dat" is written.My problem is first how can I create a ".dat" file like this , and secondly If I would have a file saved in an editor like "notepad" how can I refer to that input file?
thanks a lot.

[bash]program bob
implicit none
character(len=20) :: filename
integer :: nvals=0 , status
real :: valu
write(*,*) 'what"s the input file name:'
read(*,*) filename
write(*,1000) filename
1000 format(1X,'the name of the file is:',A)
open(unit=3,file=filename,status='old',action='read',iostat=status)
if(status==0) then
   do
      read(3,*,iostat=status) valu
      if(status /= 0) exit
      nvals=nvals+1
      write(*,1010) nvals,valu
      1010 format(1X,'For line ',I6 ,'the value is =',F10.4)
   end do
   if(status>0) then
      write(*,1020) nvals+1
      1020 format(1X,'An error occured reading line No ',I6)
   else 
      write(*,1030) nvals
      1030 format(1X,'End of file reached. There were ',I6,' values')
   end if
else
   write(*,1040) status
   1040 format(1X,'error opening file. Iostat = ', I6)
end if
close(unit=3)
end program bob[/bash]

[Steven_L_Intel1]

This sort of looks like a homework assignment.

The program expects that the file it reads is a text file with a series of numbers, one number per line. For example:

3.14
2
-456

It reads each line and then displays the line number and the value read. When it gets to the end, it exits.

You can use NOTEPAD or any text editor you like to create this file, and you can call it anything you want, though the program limits the length to 20 characters due to the declaration of variable "filename". When the program prompts you for the file name, you give the name you used. If the file is not in the program's "default directory", you'll need to give the path to the file (again subject to the 20 character limit). When running in Visual Studio, the default directory is the project directory. Otherwise it's the same directory the program executable is in.

Extra credit: Try putting things that are not numbers on a line and see what happens. Some things to try:

- Blank line
- The letter T
- A comma or a slash
- 3*4

What happens and why?

[space-tech1]

Thanks Steve

Problem sovled,I moved the file to the project folder and it worked fine,besides this is the example
in "chapman's" Fortran book page 224 chapter 5.

Thanks for your great service.