Fortran Language: Complete Guide for Beginners and Engineers

Fortran is one of the oldest and most powerful programming languages in the world. It has been used for decades to solve complex scientific and engineering problems, such as climate modeling, computational fluid dynamics, nuclear simulations, and more. But Fortran is not just a relic of the past. It is still a vibrant and evolving language, with new features and standards that make it more modern, expressive, and efficient. In this blog post, I will show you how to unlock the power of Fortran by giving you a comprehensive guide to its syntax, features, libraries, tools, and best practices. Whether you are a beginner or an expert, you will find something useful and interesting in this post. Let’s get started!

Fortran Language illustration showing scientific computing, mathematical models, and legacy to modern high-performance computing systems.

Fortran Language Tutorial

Hello, and welcome to this tutorial on Fortran, one of the oldest and most powerful programming languages in the world. Fortran stands for Formula Translation, and it was designed to perform complex mathematical calculations and scientific computing. In this tutorial, you will learn the basics of Fortran, such as how to declare variables, write expressions, create loops, use functions, and more. By the end of this tutorial, you will be able to write your own Fortran programs and run them on your computer.

Let’s start with a simple example of a Fortran program that prints “Hello, world!” to the screen. To write a Fortran program, you need a text editor and a compiler. A text editor is a software that allows you to write and edit plain text files. A compiler is a software that translates your source code into executable code that can run on your computer. There are many text editors and compilers available for Fortran, but for this tutorial, we will use gfortran, which is a free and open source compiler that works on Windows, Linux, and Mac OS.

    Foundational and overview Fortran Language

    In this tutorial, we will cover the following topics:

    • Introduction to Fortran Programming Language
    • What Is Fortran Language?
    • History of Fortran Language: From FORTRAN to Modern Fortran
    • Why Fortran Is Still Used in Scientific Computing
    • Features of Modern Fortran
    • Applications of Fortran in Engineering and HPC
    • Advantages and Disadvantages of Fortran Language
    • Is Fortran Dead or Still Relevant in 2026?
    • Who Should Learn Fortran Language?
    • Fortran Language Roadmap for Beginners
    • How Fortran Evolved from FORTRAN 77 to Fortran 2023

    Installation, setup, and toolchain Fortran Language

    • How to Install gfortran on Windows
    • How to Install gfortran on Linux
    • How to Install Fortran Compiler on macOS
    • How to Write and Run Your First Fortran Program
    • Best Fortran Compilers for Beginners and Professionals
    • gfortran vs Intel Fortran vs LLVM Flang
    • How to Compile Fortran Code from Command Line
    • How to Use Visual Studio Code for Fortran Development
    • Best IDEs and Editors for Fortran Programming
    • How to Debug Fortran Programs
    • How to Use Makefiles with Fortran
    • Introduction to Fortran Package Manager (fpm)
    • How to Install and Use fpm in Fortran Projects
    • How to Build a Modern Fortran Project Structure

    Fortran program structure basics

    • Structure of a Fortran Program
    • Program, Module, Subroutine, and Function in Fortran
    • Fortran Source File Extensions Explained
    • Fixed Form vs Free Form in Fortran
    • Case Sensitivity in Fortran
    • Comments in Fortran
    • Statements, Blocks, and Scope in Fortran
    • Identifiers, Naming Rules, and Reserved Words in Fortran
    • How Compilation Works in Fortran

    Basic syntax and beginner programming

    • Basic Syntax of Fortran Language
    • Variables in Fortran
    • Constants and Parameters in Fortran
    • Data Types in Fortran
    • Type Declaration Statements in Fortran
    • Operators in Fortran
    • Arithmetic Operators in Fortran
    • Relational and Logical Operators in Fortran
    • Assignment Statements in Fortran
    • Input and Output Basics in Fortran
    • PRINT, READ, and WRITE Statements in Fortran
    • How to Take User Input in Fortran
    • Simple Example Programs in Fortran for Beginners

    Control flow and decision-making

    • IF Statement in Fortran
    • IF ELSE and ELSE IF in Fortran
    • SELECT CASE in Fortran
    • DO Loop in Fortran
    • DO WHILE Loop in Fortran
    • Nested Loops in Fortran
    • EXIT and CYCLE Statements in Fortran
    • GOTO Statement in Fortran
    • When to Avoid GOTO in Modern Fortran
    • Block Constructs in Fortran

    Arrays and numerical core

    • Arrays in Fortran
    • One-Dimensional Arrays in Fortran
    • Two-Dimensional Arrays in Fortran
    • Multi-Dimensional Arrays in Fortran
    • Array Declaration and Initialization in Fortran
    • Array Slicing in Fortran
    • Whole Array Operations in Fortran
    • Array Intrinsics in Fortran
    • Dynamic Arrays in Fortran
    • Allocatable Arrays in Fortran
    • Automatic Arrays in Fortran
    • Assumed-Shape Arrays in Fortran
    • Explicit-Shape vs Assumed-Shape Arrays in Fortran
    • Array Bounds and Indexing in Fortran
    • Vectorization in Fortran
    • WHERE Construct in Fortran
    • FORALL in Fortran and Why It Became Less Important
    • MATMUL, DOT_PRODUCT, and Numerical Array Operations in Fortran

    Character and string handling

    • Character Data Type in Fortran
    • Strings in Fortran
    • String Concatenation in Fortran
    • Substring Handling in Fortran
    • String Comparison in Fortran
    • Character Arrays in Fortran
    • Common String Functions in Fortran

    Procedures and modular programming posts

    • Subroutines in Fortran
    • Functions in Fortran
    • Difference Between Function and Subroutine in Fortran
    • Argument Passing in Fortran
    • INTENT IN, OUT, and INOUT in Fortran
    • Optional Arguments in Fortran
    • Keyword Arguments in Fortran
    • Recursive Procedures in Fortran
    • Pure Procedures in Fortran
    • Elemental Procedures in Fortran
    • Internal Procedures in Fortran
    • External Procedures in Fortran
    • Interface Blocks in Fortran
    • Explicit Interfaces in Fortran
    • Modules in Fortran
    • USE Statement in Fortran
    • Public and Private in Fortran Modules
    • Submodules in Fortran
    • How to Organize Large Fortran Projects Using Modules

    Derived types, pointers, and memory

    • Derived Types in Fortran
    • Structure-Like Data Modeling in Fortran
    • Type-Bound Procedures in Fortran
    • Pointers in Fortran
    • Allocatable vs Pointer in Fortran
    • Dynamic Memory Allocation in Fortran
    • ALLOCATE and DEALLOCATE in Fortran
    • Pointer Association in Fortran
    • Target and Pointer Attributes in Fortran
    • Memory Management Best Practices in Fortran
    • Common Memory Errors in Fortran

    Object-oriented Fortran

    • Object-Oriented Programming in Fortran
    • Type Extension and Inheritance in Fortran
    • Polymorphism in Fortran
    • Abstract Types in Fortran
    • Deferred Bindings in Fortran
    • Class vs Type in Fortran
    • Type-Bound Procedures Explained
    • OOP Features Introduced in Fortran 2003
    • When to Use OOP in Fortran Projects
    • OOP in Fortran vs C++

    Input/output and formatting posts

    • File Handling in Fortran
    • Formatted I/O in Fortran
    • Unformatted I/O in Fortran
    • READ Statement in Detail
    • WRITE Statement in Detail
    • PRINT Statement in Detail
    • OPEN Statement in Fortran
    • CLOSE Statement in Fortran
    • INQUIRE Statement in Fortran
    • FORMAT Statement in Fortran
    • Format Descriptors in Fortran
    • List-Directed I/O in Fortran
    • Sequential Files in Fortran
    • Direct Access Files in Fortran
    • Stream Access in Fortran
    • Binary File Handling in Fortran
    • CSV File Reading and Writing in Fortran
    • Error Handling in Fortran I/O
    • End-of-File and IOSTAT Handling in Fortran

    Intrinsic procedures and standard library topics

    • Intrinsic Functions in Fortran
    • Mathematical Intrinsic Functions in Fortran
    • Array Intrinsic Functions in Fortran
    • Character Intrinsics in Fortran
    • Bit Manipulation Intrinsics in Fortran
    • Kind Selection in Fortran
    • Precision Handling in Fortran
    • SELECTED_REAL_KIND and SELECTED_INT_KIND in Fortran
    • Random Number Generation in Fortran
    • Date and Time Functions in Fortran

    Numerical programming and scientific computing

    • Why Fortran Is Fast for Numerical Computing
    • Numerical Methods Implementation in Fortran
    • Matrix Operations in Fortran
    • Solving Linear Equations in Fortran
    • Fortran for Differential Equations
    • Fortran in Finite Element Analysis
    • Fortran for Computational Fluid Dynamics
    • Fortran in Weather Modeling
    • Fortran in Scientific Simulation
    • Precision, Stability, and Performance in Fortran
    • How Array Syntax Improves Numerical Code in Fortran
    • BLAS and LAPACK with Fortran
    • Calling Scientific Libraries from Fortran

    Parallel programming and HPC posts

    • Parallel Programming in Fortran
    • Introduction to Coarrays in Fortran
    • Images in Coarray Fortran
    • Teams and Events in Coarray Fortran
    • Collective Operations in Coarray Fortran
    • DO CONCURRENT in Fortran
    • Shared Memory vs Distributed Memory in Fortran
    • Fortran with OpenMP
    • Fortran with MPI
    • Coarrays vs MPI in Fortran
    • High Performance Computing with Fortran
    • How Fortran Supports Parallel Scientific Applications
    • Performance Tuning Techniques in Fortran
    • Compiler Optimization Flags for Fortran
    • Profiling Fortran Applications

    Interoperability and mixed-language programming posts

    • Fortran and C Interoperability
    • ISO_C_BINDING in Fortran
    • How to Call C Functions from Fortran
    • How to Call Fortran Code from C
    • Mixed C and Fortran Projects
    • Fortran with Python Integration
    • Using f2py with Fortran
    • Fortran with MATLAB Integration
    • Fortran Libraries in Modern Software Stacks
    • Building Reusable Fortran Libraries

    Error handling, debugging, and best practices posts

    • Common Errors in Fortran Programming
    • How to Debug Fortran Code Effectively
    • Segmentation Faults in Fortran: Causes and Fixes
    • Array Bound Errors in Fortran
    • Type Mismatch Errors in Fortran
    • Uninitialized Variables in Fortran
    • Compiler Warnings in Fortran
    • Fortran Coding Standards and Best Practices
    • How to Write Clean Modern Fortran Code
    • How to Refactor Old FORTRAN 77 Code
    • Unit Testing in Fortran
    • Documentation Practices for Fortran Projects

    Legacy FORTRAN and modernization posts

    • FORTRAN vs Fortran: What Is the Difference?
    • Understanding Legacy FORTRAN 77 Code
    • Common FORTRAN 77 Statements Explained
    • Fixed-Form Source Code in Old FORTRAN
    • COMMON Blocks in FORTRAN
    • EQUIVALENCE in FORTRAN
    • Statement Functions in FORTRAN
    • Obsolete Features in Modern Fortran
    • How to Modernize Legacy Fortran Codebases
    • Migrating FORTRAN 77 to Modern Fortran
    • Challenges in Maintaining Old Fortran Software

    Standards and language evolution posts

    • Fortran 77 Features
    • Fortran 90 Features
    • Fortran 95 Features
    • Fortran 2003 Features
    • Fortran 2008 Features
    • Fortran 2018 Features
    • What Is New in Fortran 2023
    • Fortran Standards Timeline Explained
    • Modern Fortran vs Legacy Fortran
    • Important Language Changes Across Fortran Standards

    FAQ’s of Fortran Programming Language

    What is Fortran, and why is it still relevant today?

    Fortran is a high-level programming language designed for scientific and numerical computing. It remains relevant due to its historical significance, excellent performance in mathematical calculations, and extensive library support for scientific applications. Many legacy codes are written in Fortran, making it necessary for maintaining and updating critical scientific software.

    What are the main versions of Fortran?

    Fortran has evolved through various versions, including Fortran 77, Fortran 90, Fortran 95, Fortran 2003, Fortran 2008, and Fortran 2018. Each version introduced new features and improved the language’s capabilities, with Fortran 2018 being the most recent standard.

    How does Fortran handle arrays and matrices?

    Fortran provides robust support for arrays and matrices, making it ideal for scientific computing. You can perform array operations efficiently, and Fortran’s array syntax is concise. Arrays are indexed starting from 1, which is different from some other programming languages.

    Is Fortran suitable for modern programming practices?

    Yes, Fortran has evolved to incorporate modern programming practices. Newer standards like Fortran 90 and beyond introduced features like dynamic memory allocation, user-defined data types, and improved support for modular programming, making Fortran more in line with contemporary programming languages.

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