Compile

Single file ​

Most basic command for compiling:

g++ -o myapp main.cpp

Adding some options may help debugging for development:

g++ -o myapp -Wall -Wextra -Werror main.cpp

Example of a hello world program:

#include <iostream>
 
int main()
{
    std::cout << "Hello World!" << std::endl;
    return 0;
}

For more printing features, use the fmt library (add -lfmt to CFLAGS) and write the code like this:

#include <fmt/base.h>

int main() {
    fmt::print("Hello, world!\n");
    return 0;
}

Makefile ​

We have to teach Makefile how to compile .cpp files into .o files. This step is not needed in C, but needed in C++.

CXX = g++
CXXFLAGS = -Wall -Wextra -Werror $(EXTRA_CFLAGS)
OBJ = main.o
TARGET = myapp

.PHONY: build clean

build: $(OBJ)
	$(CXX) $(CXXFLAGS) -o $(TARGET) $(OBJ)

%.o: %.cpp
	$(CXX) $(CXXFLAGS) -c $< -o $@

clean:
	rm -f $(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.cpp

• src/main.cpp 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 CXX)
add_executable(myapp src/main.cpp)

# Dependencies
find_package(fmt REQUIRED)
target_link_libraries(myapp PRIVATE fmt::fmt)

# Installation
install(TARGETS myapp DESTINATION bin)

myapp here will be name of the binary generated.

This example is also showing to add a library (fmt) as dependency.

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