Build with gfortran and make

-Wall -Wextra -fcheck

Strict flags turn silent bugs into loud compile time errors. Wall and Wextra enable useful warnings while fcheck adds runtime checks for bounds and more. Keep them on for debug builds from day one.

gfortran -Wall -Wextra -fcheck=all -g app.f90 -o app

./app

n = 42

-J module dir

Modules compile to .mod files that other units import at build time. The -J flag chooses the directory for those files so build roots stay clean. The -I flag tells later compiles where to find them.

mkdir -p build_mods

gfortran -J build_mods -c utils.f90

gfortran -I build_mods main.f90 utils.o -o app

Minimal Makefile

A minimal Makefile rebuilds only stale files with one word: make. List object files as prerequisites of the app target and add a pattern rule for compiling. A clean target removes build artifacts. Recipe lines below start with a tab character, which make requires.

FC = gfortran FFLAGS = -Wall -Wextra -fcheck=all app: main.o utils.o $(FC) $(FFLAGS) main.o utils.o -o app %.o: %.f90 $(FC) $(FFLAGS) -c $< -o $@ clean: rm -f app *.o *.mod .PHONY: clean

make

gfortran -Wall -Wextra -fcheck=all -c main.f90 -o main.o gfortran -Wall -Wextra -fcheck=all -c utils.f90 -o utils.o gfortran -Wall -Wextra -fcheck=all main.o utils.o -o app

fpm concept

The Fortran package manager fpm wraps this workflow in standard commands. Fpm new starts a layout, fpm build compiles, and fpm test runs the suite. Learn the concept here and install the tool when a project outgrows plain makefiles.

fpm new demo

fpm build

fpm test

Next: Debugging

Article author: Arthur Isaev