An introduction to the build pipeline, and how we can orchestrate it manually

Before working with CMake, it's useful to understand the tools it orchestrates. This lesson guides you through setting up a C++ toolchain.

Building C++ Programs

Walking through the steps of the C++ compilation process, from source code to machine code.

The Compilation Pipeline

The linker's role in the build process, how it resolves symbols to combine object files, and how to troubleshoot common errors.

Object Files and the Linking Process

The difference between static and dynamic libraries, how to create them, and the trade-offs between them.

Static and Shared Libraries

The C++ Build Process

Recommended approaches for managing large projects and the libraries that they depend on

Learn how to structure your C++ projects for scalability and maintainability, from basic directory layouts to managing multiple modules.

Organizing a C++ Project

Learn to manage third-party libraries in C++, covering include/library paths, static vs. shared libraries, versioning, and platform differences.

Managing Libraries and Dependencies

An introduction to traditional build tools like Makefiles and IDE projects, highlighting the maintenance, scalability, and cross-platform challenges that result

Automated Build Systems and Their Limitations

Project Structure and Dependency Management

Setting up CMake and creating your first project

An introduction to CMake, the cross-platform, open-source meta-build system that solves the core challenges of C++ project management.

Why CMake?

A step-by-step guide to installing CMake. We'll explore command-line, GUI, and IDE workflows, and how to configure your compiler.

Setting Up a CMake Environment

Creating the bare minimum `CMakeLists.txt` file and build up to a project with an executable and a library, learning the fundamental commands along the way.

Writing a CMakeLists File

Learn the two-stage process of building a CMake project. This lesson covers configuring, generating, building, running, and troubleshooting common errors.

Building and Running CMake Projects

Learn how to organize large C++ projects in CMake using subdirectories and the `add_subdirectory()` command to create modular, maintainable builds.

CMake Project Structure and Subdirectories

Introducing CMake

Exploring CMake's programming features, caching mechanisms, and interactions with the file system

A primer on the fundamental building blocks of the CMake language: variables, string interpolation, and logging messages.

CMake Variables and Logging

Discover the CMake Cache, the mechanism for storing persistent user-configurable options, and learn how to create and manage cached variables.

The CMake Cache

Exploring CMake's command syntax and its list data type, including how to create, manipulate, and use lists in your projects.

CMake Commands, Arguments, and Lists

Transform your static build descriptions into dynamic scripts with CMake's control flow commands, if() and foreach().

CMake Conditionals and Loops

Exploring CMake's `file()` command, covering how to read, write, copy, and glob files, and how to manipulate paths.

Working with the File System

Learn to create reusable logic with CMake functions and macros, and how to organize them into modules for clean, scalable build systems.

Modularizing CMake Code

CMake Language and Fundamentals

Learn more about targets, and how their properties and links are the foundation of modern CMake

Learn to work with target properties - understanding their purpose, setting and updating them, and retrieving them when your build requires it

Target Properties

Learn about target types, and how the `PUBLIC`, `PRIVATE`, and `INTERFACE` keywords control how properties are shared.

Relationships Between Targets

Discover how CMake's `target_link_libraries()` command builds a dependency graph, and how it uses this graph to automatically manage transitive dependencies and link order.

Indirect Relationships and the Dependency Graph

Learn to use abstract target types like `INTERFACE`, `ALIAS`, and `IMPORTED` to model complex project needs, organize build properties, and integrate pre-compiled binaries.

Using `INTERFACE`, `ALIAS`, and `IMPORTED` Libraries

Adding support for user-configurable library types and an initial introduction to target installation.

Using Shared Libraries

Targets and Dependencies

Learn how to manage multiple build configurations within the same project, and how to create scripts that adapt to the environment

Learn how CMake manages different build configurations like Debug and Release, the difference between generator types, and how to apply settings conditionally using modern techniques.

Build Configurations (Debug, Release, etc.)

Learn the tools and patterns needed to write portable CMakeLists.txt files that work seamlessly across platforms and compilers

Cross-Platform Configurations

Learn to write architecture-aware CMake scripts for 32/64-bit systems and Apple's Universal Binaries (Intel/ARM).

Handling Different Architectures

Learn to build for different operating systems and architectures using CMake's cross-compilation support and toolchain files.

Cross-Compilation and Toolchain Files

Platforms and Build Configurations

Learn how to add external libraries to our build, and how to create our own packages for others to use

Learn to find and use pre-installed libraries with `find_package()`, understanding Module vs. Config mode and the power of imported targets

Finding Dependencies using `find_package()`

Learn how to make your libraries consumable by other projects using CMake by turning your build-tree into a distributable install-tree.

Creating a Consumable Package

Learn how to consume a CMake package you've installed, completing the producer-consumer cycle. We'll cover using `find_package()` and how to point CMake to your library's location

Using Installed Packages

Learn how to create self-contained, reproducible builds by fetching dependencies from source using `FetchContent()` and `ExternalProject_Add()`.

Fetching External Dependencies

Creating and Consuming Packages

Integrating the vcpkg and Conan package managers to handle external dependencies

Learn to manage C++ dependencies effortlessly with the vcpkg package manager and its seamless CMake integration using toolchain files and manifests.

Integrating CMake and vcpkg

Learn the day-to-day commands for managing dependencies with vcpkg and how to guarantee reproducible builds using baselines and version overrides

vcpkg Commands and Versioning

Combine vcpkg with CMake's cross-compilation capabilities. Learn to use triplets to target different architectures and chain-load toolchain files

Cross-Compiling with vcpkg

Discover Conan, the binary-first C++ package manager, and learn how to integrate it with CMake using profiles and lockfiles for fast, reproducible builds.

Using Conan with CMake

Learn to cross-compile C++ projects with Conan, using build and host profiles to manage dependencies for different platforms.

Cross-Compilation with Conan

Package Managers

Introducing presets, allowing us to simplify our workflow and share common configurations across our team

Learn the fundamentals of CMake Presets. This lesson introduces `CMakePresets.json` to simplify complex build commands.

CMake Presets

Learn to structure your CMake presets with inheritance and customize them for your local environment using `CMakeUserPresets.json`.

User Presets and Inheritance

Learn to make your CMake presets portable by using environment variables and conditional logic to adapt to different machine configurations.

Environment Variables and Conditional Presets

Learn how to extend the build process beyond simple compilation by integrating external tools and custom commands

Learn how to use generator expressions `$<...>` for build-time conditional logic.

Generator Expressions and Conditional Logic

Learn how to attach commands to specific points in a target's build lifecycle using `add_custom_command(TARGET)` for tasks like post-build file copying.

Integrating Tools with `add_custom_command()`

Learn to integrate code generators like Protobuf into your build process using `add_custom_command()`, creating automated file-level dependencies in CMake.

Generating Files with Protobuf and `add_custom_command()`

Custom Commands

An introduction to automating common workflow chores by creating custom targets

Learn to create standalone, non-code targets using add_custom_target() for utility tasks like code formatting and documentation generation.

Custom Targets and Build Utilities

Using the Clang-Format tool to automatically enforce a consistent coding style, and integrating it into our build using a custom CMake target

Using Clang-Format

An introduction to file sets and the `target_sources()` command, allowing us to manage our header files in a more controlled way

Using File Sets

A step-by-step guide to integrating Doxygen into your CMake build process for automated C++ documentation.

Generating Documentation with Doxygen

Custom Targets

Integrate automated tests into a CMake project using CTest, GoogleTest, and GoogleMock

Learn the fundamentals of automated testing in C++ with CTest. Create your first test suite, register tests with `add_test()`, and run them with the `ctest` command.

Automated Testing and CTest

Learn to refactor manual C++ tests into a professional test suite using the GoogleTest framework, managed by vcpkg and integrated with CTest.

Integrating GoogleTest with CMake

Learn to use a wide range of assertions, write data-driven parameterized tests, and isolate dependencies with Google Mock.

Assertions and Parameterized Tests

Learn how to isolate dependencies that our project uses, and then how to replace those dependencies at test time using Google Mock.

Dependency Injection and Mocking

Learn the standard pattern for testing application logic by refactoring it into a linkable library

Testing Executables

Move beyond individual tests to manage a full test suite. Learn to organize tests, run tests in parallel, filter by labels, and measure our code coverage

Managing a Test Suite

Automated Testing

Using static and dynamic analysis in CMake projects to automatically detect memory bugs, performance issues, and problematic code

Learn to find memory bugs at runtime by integrating AddressSanitizer (ASan) into a CMake project

Using AddressSanitizer (ASan)

Adding benchmarks to our build to measure the performance of our code, and track how it changes over time

Using Google Benchmark

Integrating Clang-Tidy to enforce good practices and find bugs before we even compile

Using Clang-Tidy

Automated Analysis

Automating the entire development lifecycle using Git for souce control, GitHub Actions for cloud builds, and CPack to create distributable packages and installers.

An introduction to Git, the version control system that underpins modern collaborative software development and automated build pipelines.

Source Control with Git

Learn how to automate your build and test process with Continuous Integration (CI) and a build server. This lesson provides a guide to creating a GitHub Actions workflow for a CMake project.

Build Servers and Continuous Integration

Learn to package your C++ projects using CMake's CPack. This lesson covers creating developer ZIP archives and professional Windows MSI installers with components.

Packaging with CPack

Learn to automate the packaging process by integrating CPack with a multi-platform GitHub Actions workflow

Packaging with GitHub Actions

Learn to automate the creation of a professional Windows installer by integrating CPack, the WiX Toolset, and a multi-platform GitHub Actions workflow.

Creating Installers with CPack and GitHub Actions

Learn to automate the release process using a GitHub Actions workflow that builds, packages, and publishes artifacts to a GitHub Release

Deployment with GitHub Releases

Continuous Integration and Packaging

If you have a basic grasp of C++ but find the build process intimidating, this course is for you. We assume you know the language, but not how to manage large projects.

Manage complex, cross-platform builds using industry-standard tools. Create scalable build systems that automate the entire development lifecycle.

This course is a comprehensive deep-dive into the entire C++ build ecosystem, centered around the power and flexibility of modern CMake. We leave no stone unturned.

Start with a foundational understanding of compilers, linkers, static vs. shared libraries, and object files.

The Full Build Pipeline

Learn every aspect of the CMake language, from variables and control flow to functions, modules, and generator expressions.

Complete CMake Language Mastery

Master the modern target-centric paradigm, including properties, usage requirements, and abstract targets.

Advanced Target Management

Explore every method for handling dependencies, from `find_package` and `FetchContent` to vcpkg and Conan, including versioning and cross-compilation.

In-Depth Dependency Management

Integrate a full suite of professional tools for testing (CTest, GoogleTest), analysis (ASan, Clang-Tidy), and packaging (CPack).

Total Workflow Automation

Build a fully automated deployment pipeline that takes your code from a Git push to a published GitHub Release with multi-platform installers.

End-to-End CI/CD and Deployment

What You'll Learn

Become a software engineer with C++.  Starting from the basics, we guide you step by step along the way

Intro to C++ Programming

If you're completely new to programming or want a thorough introduction, consider starting with our free introductory course:

New to Programming?

Managing C++ Projects Using CMake

One of the goals of our build configuration is to have it be portable. The dream is to write one `CMakeLists.txt` file, and have any developer on any machine - Windows, macOS, or Linux- be able to build the project with a few simple commands.


In the <InlineLessonPromo url="cmake/cmake-build-configurations" title="Build Configurations (Debug, Release, etc.)" description="Learn how CMake manages different build configurations like Debug and Release, the difference between generator types, and how to apply settings conditionally using modern techniques.">previous lesson</InlineLessonPromo>, we took a major step toward this by using generator expressions, which let us handle different build configurations in a portable way.


Now, we'll tackle the next layer of complexity: handling differences between operating systems and compilers. C++ code is often portable, but the environment it builds and runs in is not. File paths, compiler flags, and system libraries all have platform-specific quirks.


This lesson will cover the main tools to write a universal `CMakeLists.txt`. We'll learn how to detect the host system and compiler, and how to use that information to conditionally include source files, set compiler flags, and link against the correct libraries for the target platform.


## Working With Paths


A path written for one OS will break on another:


```c++
//<cmake>
# Bad: Windows-specific backslashes
set(MY_SOURCES "src\\main.cpp")#<w>
```


Instead, always use forward slashes (`/`) for paths. CMake will automatically convert them to the native format (`\\`) on Windows.


```c++
//<cmake>
# Good: Use / by default
set(MY_SOURCES "src/main.cpp")#<h>
```


More importantly, using exact absolute path to where things are on **your** hard drive will not work for people storing the project in a different location:


```c++
//<cmake>
target_include_directories(MyTarget PUBLIC
  # Bad: Absolute path
  "/usr/greg/my-project/include"#<w>
)
```


Instead, always construct paths that are **relative** to the project structure.  The CMake variables we covered earlier in the course, such as `PROJECT_SOURCE_DIR`, can help with this:


```c++
//<cmake>
target_include_directories(MyTarget PUBLIC
  # Good: Relative Path
  "${PROJECT_SOURCE_DIR}/include"#<h>
)
```


## Detecting the Operating System


CMake automatically defines a set of boolean variables that tell you which platform you're configuring for. These variables allow you to create conditional blocks that execute only on a specific OS. The three most important are:

- `WIN32`: True on all versions of Windows, including 64-bit.
- `APPLE`: True on all Apple operating systems, including macOS and iOS.
- `UNIX`: True on all UNIX-like systems, which notably includes both Linux and macOS (`APPLE` systems are also `UNIX`).

The most common pattern is to check for Windows first, and then treat everything else as Unix-like.


### Example: Platform-Specific Source Files


Let's expand on an example from a previous lesson. Imagine our `GreeterLib` needs to display the current operating system, which requires calling a platform-specific API.


First, we'll define a common interface in our public header.


<CodeFile path="greeter/include/greeter/Greeter.h" status="Updated">


```c++
#pragma once
#include <string>

std::string get_greeting();
std::string get_os_string(); // New function //<h>
```


</CodeFile>


Next, we'll provide two different implementations for this function.


<CodeViewer>


<CodeFile path="greeter/src/platform_win.cpp" status="New">


```c++
#include <greeter/Greeter.h>

std::string get_os_string() {
  return "This is Windows!";
}
```


</CodeFile>


<CodeFile path="greeter/src/platform_nix.cpp" status="New">


```c++
#include <greeter/Greeter.h>

std::string get_os_string() {
  return "This is a Unix-like system!";
}
```


</CodeFile>


</CodeViewer>


Finally, in `greeter/CMakeLists.txt`, we use an `if()` block to choose which source file to compile into our library.


<CodeFile path="greeter/CMakeLists.txt" status="Updated">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)

set(LIB_SOURCES src/Greeter.cpp) #<h>

if(WIN32) #<h>
  list(APPEND LIB_SOURCES src/platform_win.cpp) #<h>
else() # We assume anything not Windows is Unix-like #<h>
  list(APPEND LIB_SOURCES src/platform_nix.cpp) #<h>
endif() #<h>

add_library(GreeterLib ${LIB_SOURCES})#<h>

target_include_directories(GreeterLib PUBLIC
  "${CMAKE_CURRENT_SOURCE_DIR}/include"
)
```


</CodeFile>


Now, the `GreeterLib` target will be built with the correct implementation file for the host OS, while the interface (`Greeter.h`) remains consistent for all consumers.  We no longer need to perform this platform check in our code - out build system is taking care of it:


<CodeFile path="app/src/main.cpp" status="New">


```c++
#include <iostream>
#include <greeter/Greeter.h>

int main() {
  std::cout << get_greeting();
  std::cout << '\n' << get_os_string();
  return 0;
}
```


</CodeFile>


```c++
//<o>
Hello from the modular greeter library!
This is Windows!
```


<Aside>


### Cross-Compilation and `CMAKE_HOST` Variables


What happens when you're building **on** one platform but **for** another? For example, you might be using a Windows machine to create a program that runs on Linux. This is called **cross-compilation**, which we cover in detail later in this chapter.


For now, we should note that the variables we've discussed in this section (`WIN32`, `UNIX`, and `APPLE`) always describe the _**target**_ system, where the code will eventually be run.


If we need to inspect the **host** system, where CMake is running, you can use the variables `CMAKE_HOST_WIN32`, `CMAKE_HOST_UNIX`, and `CMAKE_HOST_APPLE`.


</Aside>


<Pw>


## Abstract Away Platform Details


In addition to removing platform-specific logic from our code, a good goal is to minimize the amount of platform-specific logic even in our build scripts.


For example, the following approach duplicates platform logic to link `SomeLibrary` to targets, but only on Windows:


```c++
//<cmake>
# App1 needs a windows-specific library
if(WIN32) #<w>
  target_link_libraries(App1 PRIVATE SomeLibrary) #<w>
endif() #<w>

# Bad: App2 duplicates the same logic
if(WIN32) #<w>
  target_link_libraries(App2 PRIVATE SomeLibrary) #<w>
endif() #<w>
```


Instead of scattering `WIN32` checks everywhere, you might create an `INTERFACE` target that encapsulates the platform-specific detail:


```c++
//<cmake>
# Create an INTERFACE target to represent platform dependencies
add_library(PlatformLibs INTERFACE) #<h>

# In one place, add the windows library to the interface
if(WIN32) #<h>
  target_link_libraries(PlatformLibs INTERFACE SomeWindowsLibrary) #<h>
endif() #<h>
```


Consumers now link to the abstraction - no further `Win32` checks needed:


```c++
//<cmake>
target_link_libraries(App1 PRIVATE PlatformLibs) #<h>
target_link_libraries(App2 PRIVATE PlatformLibs) #<h>
```


### Example: Linking System Libraries


The most common cross-platform challenge is linking against system libraries, which often have different names or don't exist at all on other platforms.


For example, Windows applications that use networking sockets often need to link against the `ws2_32.lib` library. On Linux and macOS, this functionality is part of the standard library and doesn't require an explicit link.


Let's create a `Networking` library that implements this platform-specific dependency.


<CodeFile path="networking/CMakeLists.txt" status="New">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)

add_library(Networking INTERFACE)

# On Windows, we need to link the sockets library.
if(WIN32) #<h>
  target_link_libraries(Networking INTERFACE ws2_32) #<h>
endif() #<h>
```


</CodeFile>


In our root `CMakeLists.txt`, we can add this new subdirectory.


<CodeFile path="CMakeLists.txt" status="Updated">


```c++
#<cmake>
add_subdirectory(greeter)
add_subdirectory(app)
add_subdirectory(networking) #<h>
```


</CodeFile>


Now, any target in our project that needs networking can simply link against our abstract `Networking` target:


<CodeFile path="app/CMakeLists.txt" status="Updated">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)

add_executable(GreeterApp src/main.cpp)
target_link_libraries(GreeterApp GreeterLib)
target_link_libraries(GreeterApp Networking)#<h>
```


</CodeFile>


Again, note that the consumer - `GreeterApp` in this case - does **not** need to perform any platform checks here.  It doesn't need to know _why_ or _how_ networking works; it just needs to state its requires networking support, expressed by linking to the `Networking` interface.


If this project is configured on Windows, the `Networking` target will carry the `ws2_32` link dependency with it, and `SomeOtherTarget` will be correctly linked. If configured on Linux, the `Networking` target will have no link dependencies, and nothing extra will be added to the link line.


## Detecting the Compiler


Just as with the operating system, CMake detects the compiler being used and sets several variables accordingly. This is helpful for setting compiler-specific flags or working around compiler-specific bugs.


The most common variables for checking the compiler family are:

- `MSVC`: True if the compiler is Microsoft Visual C++ (or a compatible front-end like `clang-cl`).
- `GNU`: True for the GNU Compiler Collection (GCC).
- `Clang`: True for the Clang compiler.

### Example: Compiler-Specific Warning Flags


In a previous lesson, we created an `INTERFACE` library called `StrictWarnings` to apply a set of warning flags. However, the flags we used (`-Wall`, `-Wextra`) were specific to GCC and Clang. They will cause an error if used with MSVC.


We can make our `StrictWarnings` target portable by detecting the compiler and setting the appropriate flags for each one.


<CodeFile path="CMakeLists.txt" status="Updated">


```c++
#<cmake>
cmake_minimum_required(VERSION 3.16)
project(Greeter VERSION "1.0")

add_library(StrictWarnings INTERFACE)#<h>

if(MSVC) #<h>
  # Use Microsoft-specific warning level 4 #<h>
  target_compile_options(StrictWarnings INTERFACE /W4) #<h>
else() #<h>
  # Assume GCC/Clang-compatible flags for others #<h>
  target_compile_options(StrictWarnings INTERFACE #<h>
    -Wall #<h>
    -Wextra #<h>
    -Wpedantic #<h>
  ) #<h>
endif() #<h>

add_subdirectory(greeter)
add_subdirectory(app)
```


</CodeFile>


Now, our `StrictWarnings` target is a portable abstraction. Any internal target can link against it and receive the correct, most stringent warning level for whatever compiler is being used, without the target needing to know any of the compiler-specific details.


```c++
//<cmake>
target_link_libraries(MyTarget PRIVATE StrictWarnings)
```


## Summary


Writing portable CMake scripts is about abstracting away platform differences. By using CMake's introspection variables, you can create a `CMakeLists.txt` that correctly assembles the right source files, compiler flags, and library links for any environment.

- **Stay Portable**: Avoid hardcoded paths and platform-specific commands. Use CMake's variables (`${PROJECT_SOURCE_DIR}`) and commands (`target_link_libraries`) to express your intent.
- **Detect the OS**: Use `if(WIN32)`, `if(APPLE)`, and `if(UNIX)` to create conditional blocks for OS-specific logic.
- **Detect the Compiler**: Use `if(MSVC)`, `if(GNU)`, and `if(Clang)` to set compiler-specific flags or work around compiler differences.
- **Abstract Dependencies**: When dealing with platform-specific libraries or source files, create an `INTERFACE` target to represent the abstract dependency. Consumers can then link to this portable target, and the platform-specific details will be handled automatically.

</Pw>

cmake-language(7) Manual

Variables that Describe the System

CMake for Cross-Platform Compilation

How do you include specific libraries based on the OS in CMake?

Multiplatform C++ Project: Inclusion of platform specific sources

How I Structure Cross-Platform C++ Projects with CMake

Master cross-platform C++ development with this guide to portable CMake. Learn to detect the OS (WIN32, APPLE, UNIX) and compiler (MSVC, GNU, Clang) to conditionally include source files, set flags, and link libraries for any platform.

Writing Cross-Platform CMake: A Guide for Windows, macOS, and Linux

Cross-Compilation and `CMAKE_HOST` Variables

Cross-Platform Configurations

Understanding the Basics

Practical Applications

Common Mistakes

Next Steps

Additional Resources

Assessment Preparation

Managing C++ Projects Using CMake