fortran — consolidated language guide — DedSec Project

Fortran

Typical use: Scientific and numerical computing.

Suggested file extension: .f90.

How to run / environment: gfortran hello.f90 -o hello && ./hello.

Starter example

program hello
  implicit none
  character(len=*), parameter :: name = 'Ada'
  print *, 'Hello, ', name, '!'
end program hello

How to read it

Use implicit none to catch undeclared variables.

Common pitfall

Use implicit none to catch undeclared variables.

Fortran — Expanded practice workbook

Inspect the smallest source

program hello
  implicit none
  character(len=*), parameter :: name = 'Ada'
  print *, 'Hello, ', name, '!'
end program hello

Run or compilation context: gfortran hello.f90 -o hello && ./hello.. Treat this as a baseline: save a copy, confirm the toolchain version and note whether the example merely evaluates a value, prints text, or creates external effects. Production accounts, datasets and hardware must not be used for first attempts.

Work through the actual mechanism

Implement a pure function over real(kind) arrays with explicit interfaces, verify shapes and run with bounds checking. Compare an array expression with an explicit DO loop.

Diagnose the sharp edge

Default real precision may lose significant digits; array ordering is column-major and implicit typing can hide misspellings unless implicit none is set.

Fortran — Practical runnable code lab

How to run the samples

These independent samples use the appropriate language toolchain. Representative command: gfortran {file} -o demo && ./demo. Replace placeholders with the actual filename, keep test data isolated, and do not interpret this as automatic installation.