How to get started with gfortran on a Mac?

Question

Just finished installing the compiler gfortran 6.1. El Capitan. Next, I want to know how to run a file. So, I have a few questions:

1. Which extension should I use to save the file? Is it .f90 or something else?
2. What kind of software can be used to edit and save the source code?
3. Once I save the file, how do I compile it? Is is gfortran followed by the file name (with path) in the Terminal? Also, how does the path look like on a Mac?

A step by step guide would be a great help. I am a first time Mac user. :)

Answer 1

1. .f90 for free formatted sources is commonly used
2. Any texteditor you are comfortable with and used to, vim for example
3. gfortran /your/source/file that would be with an absolute path. If you are in the directory of the source file already you do not need to specify the complete path.

Step by step "hello world":

• Create a text file with your Fortran program

• Just to give a command line example without the need for an editor (this is not what you typically would do):

  • Open the terminal, then enter

    cat >hello.f90 <<EOF
    program hello
      implicit none
      write(*,*) 'hello world'
    end program hello
    EOF
    

• Compile your program in the terminal with: gfortran hello.f90

• Execute it in the terminal with ./a.out

• If you want another name use the -o option:

  gfortran -o hello hello.f90
  ./hello