Compile

Single file ​

Most basic command for compiling:

gcc -o myapp main.c

Adding some options may help debugging for development:

gcc -o myapp -Wall -Wextra -Werror main.c

Multiple files ​

When creating header files, the structure of the files is like this:

main.c
mylib.h
mylib.c

Contents of mylib.h

#ifndef MYLIB_H
#define MYLIB_H

void custom_function(char text[]);

#endif

Contents of mylib.c

#include <stdio.h>

void custom_function(char text[]) {
    printf("Custom function was called with '%s'!\n", text);
}

Import mylib.h from main.c

#include "mylib.h"

int main() {
    char text[] = "Hello World!";
    custom_function(text);
    return 0;
}

Makefile ​

Single file, compile direct to executable.

build:
	gcc -o myapp -Wall -Wextra -Werror main.c

Multiple files, generating object files before executable.

CC = gcc
CFLAGS = -Wall -Wextra -Werror $(EXTRA_CFLAGS)
OBJ = main.o mylib.o
TARGET = myapp

.PHONY: build clean

build: $(OBJ)
	$(CC) -o $(TARGET) $(CFLAGS) $(OBJ)

mylib.o: mylib.h

clean:
	rm -f $(TARGET) $(OBJ)

Build with make EXTRA_CFLAGS='-g -O0' to enable debugging with gdb.

Bellow another example with hardening options enabled:

CC = gcc
CFLAGS = -march=native -flto -Wall -Wextra -Wformat=2 -Wconversion -Wimplicit-fallthrough -Werror=format-security -Wl,-z,nodlopen -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -Wl,--no-copy-dt-needed-entries -Wtrampolines -Wbidi-chars=any -Werror=implicit -Werror=incompatible-pointer-types -Werror=int-conversion
CLIBFLAGS = -fPIC -shared
CDEVFLAGS = -g -O0 -Werror
CPRODFLAGS = -s -O2

DEBUG_DIR = target/debug
RELEASE_DIR = target/release
OBJ = src/main.o
TARGET = myapp

.PHONY: build release clean

build: $(OBJ)
	mkdir -p $(DEBUG_DIR)
	$(CC) -o $(DEBUG_DIR)/$(TARGET) $(CDEVFLAGS) $(CFLAGS) $(OBJ)

release: $(OBJ)
	mkdir -p $(RELEASE_DIR)
	$(CC) -o $(RELEASE_DIR)/$(TARGET) $(CPRODFLAGS) $(CFLAGS) $(OBJ)

clean:
	rm -f $(DEBUG_DIR)/$(TARGET) $(RELEASE_DIR)/$(TARGET) $(OBJ)

CMake ​

• An Introduction to Modern CMake

There are two steps to set up a project for CMake usage.

Add files ​

First you need to place (at least) two files to your project.

CMakeLists.txt
src
└── main.c

• src/main.c is a C program that compiles
• CMakeLists.txt is the project's configuration

A very simple CMakeLists.txt:

cmake_minimum_required(VERSION 3.24)

# Project structure
project(myapp
        VERSION 0.1.0
        LANGUAGES C)
add_executable(myapp src/main.c)

# Installation
install(TARGETS myapp DESTINATION bin)

myapp here will be name of the binary generated.

Build ​

Considering a build that will use:

First we create the build directories that includes some build configuration like the compiler and a generator. These commands have to be run only once.

cmake -GNinja -DCMAKE_BUILD_TYPE:STRING=Debug -S. -Btarget/debug
cmake -GNinja -DCMAKE_INSTALL_PREFIX:STRING=$HOME/.local -DCMAKE_BUILD_TYPE:STRING=Release -S. -Btarget/release

Then, for a debug build & run:

cmake --build target/debug
./target/debug/myapp

For a release build & install (this will install the binary into ~/.local/bin because we have CMAKE_INSTALL_PREFIX set):

cmake --build target/release
cmake --install target/release --strip

To uninstall:

xargs -d '\n' rm -v <target/release/install_manifest.txt