In this part of the tutorial, we will write our first Fortran program: the ubiquitous Hello World example.
However before we can write our program, we need to ensure that we have a Fortran compiler set up.
Note: Fortran is a compiled language which means that once written, the source code must be passed through a compiler to produce a machine executable that can be run.
To check if you have gfortran setup correctly, open a terminal and run the following command :
$> gfortran --version
this should output something like:
GNU Fortran 7.5.0 Copyright (C) 2017 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Once you have setup up your compiler, open a new file in your favourite code editor and enter the following:
program hello ! This is a comment line, it is ignored by the compiler print *, 'Hello, World!' end program hello
Having saved your program to
hello.f90, compile at the command line with:
$> gfortran hello.f90 -o hello
Note: .f90 is the standard file extension for modern fortran source files. The 90 refers to the first modern fortran standard in 1990.
To run your compiled program:
$> ./hello Hello, World!
Congratulations you’ve written, compiled and run your first Fortran program! In the next part of this tutorial we will introduce variables for storing data.