Fortran1

Fortran1: The Basics

We'll forge our path through the verdant garden of Fortran90 using a number of examples. To get your copy of these examples, from the version control repository, login to your favourite linux machine (perhaps dylan), and type:

svn co http://source.ggy.bris.ac.uk/subversion/fortran1/trunk --username=guest ./fortran1

hello, world

Without further ado, and in-keeping with the most venerable of traditions, let's meet our first example--"hello, world":

cd fortran1/examples/example1

and type:

make

Now type:

./hello_world.exe

Bingo! You've just compiled and run, perhaps your first, Fortran90 program. Hurrah! we're on our way:) Everybody whoop!

OK, you'd better reign in your excitement. Let's take a look inside the source code file. Open-up hello_world.f90, using cat, less, more or your favourite text editor, and you'll see:

!
! This is a comment line.
! Below is a simple 'hello, world' program written in Fortran90.
! It illustrates creating a main 'program' unit together
! with good habits, such as using 'implicit none' and comments.
!
program hello_world
  implicit none
  write(*,*)  "hello, world"
end program hello_world

We have:

1. some comment lines, giving us a helpful narrative
2. the start of the main program unit
3. the implicit none statement (more of that in a moment)
4. a write statement, printing our greeting to the screen
5. and last, but not least, the end of the main program.