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

In the last two lessons, we've transformed our build process with CMake Presets. We've replaced long, complex command lines with simple names, and we've used inheritance and user presets to create a scalable, layered configuration that separates team-wide standards from personal preferences.


We've solved one major problem, but another remains. Our presets still contain hardcoded paths to tools like vcpkg. Previously, we've overridden these in a `CMakeUserPresets.json` file:


<CodeFile path="CMakeUserPresets.json">


```json
{
  "version": 3,
  "configurePresets": [{
    "name": "user-windows-debug",
    "inherits": ["windows-debug"],
    "cacheVariables": {
      "VCPKG_TOOLCHAIN_FILE":
        "D:/vcpkg/scripts/buildsystems/vcpkg.cmake"
    }
  }]
}
```


</CodeFile>


This works, but still requires every developer to create a file with their specific machine's paths. This isn't ideal, especially for automated build servers which don't have a "user" to create such a file.


This lesson introduces the final pieces of the puzzle. We'll learn how to read **environment variables** to remove hardcoded paths and how to use **conditional presets** to make our build configurations intelligently adapt to the machine they're running on.


## What are Environment Variables?


An environment variable is a key-value pair that is part of your operating system's "environment". It's a global setting that can be accessed by any program or script, including CMake.


They are the standard, universal mechanism for telling tools where to find things without hardcoding paths. For example, your system's `PATH` environment variable is a list of directories that your terminal searches to find executables like `cmake`, `vcpkg`, and `conan`.


The convention for a tool like vcpkg is to set an environment variable, often named `VCPKG_ROOT`, that points to its installation directory.


## Setting Environment Variables


Let's set up the `VCPKG_ROOT` environment variable on our system. The process differs slightly between platforms.


### On Windows

1. In the Start Menu, search for and open "Edit the system environment variables".
2. In the "Advanced" tab, click the "Environment Variables..." button.
3. In the "System variables" section at the bottom, click "New...".
4. For "Variable name", enter `VCPKG_ROOT`. For Variable value, enter the path you installed vcpkg (the directory where `vcpkg.exe` is)
5. Click OK on all windows to save.
6. **Important**: You must close and reopen any terminal or IDE for the new variable to take effect.

<Img file="windows-vcpkg-environment-variable.png" alt="Screenshot of an environment variable being set in Windows" width="598" height="177" blurHash="L1RC_E0000xvn1D+D*V@00~q?bbc" />


### On macOS and Linux


Open your shell's configuration file in a text editor. This is usually `~/.zshrc` for Zsh (the default on modern macOS) or `~/.bashrc` for Bash.


Add the following line to the end of the file, replacing the path with your actual vcpkg installation directory.


```c++
export VCPKG_ROOT="/path/to/your/vcpkg"
```


Save the file and restart your terminal, or run `source ~/.zshrc` (or `source ~/.bashrc`) to apply the changes immediately.


### On MSYS2 UCRT64


The process is the same as for Linux. From within the MSYS2 terminal, edit your `~/.bashrc` file and add the `export VCPKG_ROOT="..."` line.


<Aside>


### Temporary Environment Variables


The methods above set a **persistent** environment variable that will be available in all future terminal sessions. Sometimes, you only want to set a variable for a single command or session.


**On Linux/macOS/MSYS2** we can sets a variable only for that one command using:


```c++
VCPKG_ROOT=/path/to/vcpkg cmake --preset=...
```


**On Windows CMD** we can set the variable for the current terminal session only using:


```c++
set VCPKG_ROOT=C:\path\to\vcpkg
```


It will be lost when you close the window.


**On PowerShell**, the following command also sets it for the current session:


```c++
$env:VCPKG_ROOT = "C:\path\to\vcpkg"
```


</Aside>


## Testing Environment Variables


You can verify that the variable is set correctly by opening a **new** terminal and running `echo $VCPKG_ROOT` on Linux/macOS, `echo %VCPKG_ROOT%` on Windows Command Prompt, or `$env:VCPKG_ROOT` on Windows PowerShell.


The output should be the path you just set.  For example:


```javascript
//<o>
echo $VCPKG_ROOT
```


```javascript
//<ti>
~/vcpkg
```


<Pw>


## Using Environment Variables in Presets


Now that we have a standard way to find vcpkg on any machine, we can update our preset to use it.


CMake Presets provide a special syntax, `$env{VARIABLE_NAME}`, to read the value of an environment variable.


Let's refactor our shared `_base` preset in `CMakePresets.json` to use this:


<CodeFile path="CMakePresets.json" status="Updated">


```json
{
  "version": 3,
  "configurePresets": [{
    "name": "_base",
    "hidden": true,
    "binaryDir": "${sourceDir}/build/${presetName}",
    "cacheVariables": {
      "VCPKG_TOOLCHAIN_FILE":
        "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake"//<h>
    }
  } /* Other presets unchanged */]
}
```


</CodeFile>


Any developer, on any machine, can now use a preset than inherits from this and have `VCPKG_TOOLCHAIN_FILE` automatically set.  CMake will read their local `VCPKG_ROOT` environment variable and construct the correct path to the toolchain file at configure time.


They no longer need to create user presets for this - they just need to set their `VCPKG_ROOT` environment variable.


## Conditional Presets


Our preset is portable, but what happens if a developer tries to use it without setting the `VCPKG_ROOT` environment variable? CMake will try to expand `$env{VCPKG_ROOT}`, find it's empty, and fail because the path is invalid.


The `condition` key allows you to specify a condition that must be true for the preset to be considered valid and be shown to the user.


The following shows two examples of a condition:

- The `windows-only` preset uses an `equals` condition to compare two strings, making the preset only available on Windows
- The `mac-or-linux` preset uses an `inList` condition to make the preset only available on Darwin (macOS) or Linux

<CodeFile path="CMakePresets.json" status="Updated">


```json
{
  "version": 3,
  "configurePresets": [{
    "name": "windows-only",
    "condition": {
      "type": "equals",
      "lhs": "${hostSystemName}",
      "rhs": "Windows"
    }
  }, {
    "name": "mac-or-linux",
    "condition": {
      "type": "inList",
      "string": "${hostSystemName}",
      "list": ["Darwin", "Linux"]
    }
  }]
}
```


</CodeFile>


If we list our available conditions now then, depending on our system, we should see at most one option is available to us:


```c++
//<ti>
cmake --list-presets
```


```c++
//<o>
Available configure presets:
  "mac-or-linux-preset"
```


### Combining Conditions


What if we also need to check for the presence of our `VCPKG_ROOT` environment variable? The `anyOf` or `allOf` condition type can include a `conditions` array comprising of multiple checks:


```json
{
  "version": 3,
  "configurePresets": [{
    "name": "windows-vcpkg-preset",
    "condition": {
      "type": "allOf",
      "conditions": [{
        "type": "equals",
        "lhs": "${hostSystemName}",
        "rhs": "Windows"
      }, {
        "type": "notEquals",
        "lhs": "$env{VCPKG_ROOT}",
        "rhs": ""
      }]
    }
  }]
}
```


The `allOf` type acts like a logical AND. This preset will now only be available if **all** of the nested `conditions` are true:

- the host system is Windows AND
- the `VCPKG_ROOT` environment variable is set - that is, it does `notEquals` an empty string

The [official documentation](https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html#condition) lists a few other conditional types that are available, as well as further variables that can be used similar to how we're using `${hostSystemName}` in this example.


## Environment Variables in `CMakeLists.txt`


While presets are the modern way to handle environment-specific configuration, it's also possible to read environment variables directly from within a `CMakeLists.txt` file.


The syntax is slightly different: `$ENV{VARIABLE_NAME}` (note the uppercase `ENV`).  


### Practical Example


Our build currently requires a `VCPKG_TOOLCHAIN_FILE` variable to be defined.  That definition is expected to come from the command line, either through a `-DVCPKG_TOOLCHAIN_FILE`  argument or by using a `--preset` that includes it.


However, if someone doesn't provide that argument, we could still make our build work simply by setting the variable within our `CMakeLists.txt` file.  For example:


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


```c++
#<cmake>
cmake_minimum_required(VERSION 3.21)
project(Greeter)

# Only set VCPKG_TOOLCHAIN_FILE if the user hasn't already
if(NOT DEFINED VCPKG_TOOLCHAIN_FILE AND DEFINED ENV{VCPKG_ROOT})
  set(
    VCPKG_TOOLCHAIN_FILE
    "$ENV{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake"
    CACHE FILEPATH "vcpkg toolchain file"
  )
  message(STATUS
    "Using VCPKG_ROOT from environment: $ENV{VCPKG_ROOT}"
  )
endif()

add_subdirectory(app)
```


</CodeFile>


This script checks if `VCPKG_TOOLCHAIN_FILE` has already been set. If not, it checks if the `VCPKG_ROOT` environment variable exists. If it does, it sets the toolchain file itself, caching the result.


Note that the `NOT DEFINED VCPKG_TOOLCHAIN_FILE` check here is not strictly necessary.  As we covered in our earlier lesson on <InlineLessonPromo url="cmake/the-cmake-cache" title="The CMake Cache" description="Discover the CMake Cache, the mechanism for storing persistent user-configurable options, and learn how to create and manage cached variables.">the CMake cache</InlineLessonPromo>, values provided on the command line will take precedence over our `set()` commands, unless we add the `FORCE` argument.


However, including this check anyway makes our intent clearer, and it also ensures our `message()` only shows when the `set()` command is effective.


## Summary


In this final lesson on presets, we've learned how to decouple our build configurations from the specific machines they run on, creating portable and user-friendly workflows.

- **Environment Variables**: They are the standard way to provide machine-specific information, like paths to tools, to your build system.
- **Reading Environment Variables in Presets**: Use the `$env{VAR_NAME}` syntax inside your `CMakePresets.json`.
- **Conditional Presets**: Use the `"condition"` key to control when a preset is available. This is used for creating presets that only appear when the necessary tools or environment variables are present.
- **Reading Environment Variables in** **`CMakeLists.txt`**: For fallbacks or older CMake versions, you can use `$ENV{VAR_NAME}` directly in your scripts, but the preset approach is generally preferred.

<Preview>


### Generator Expressions and Conditional Logic


We've mastered how to make decisions at **configure** time using `if()` statements and presets. But what about decisions that can only be made at **build** time, like applying a flag only for a `Debug` build when using a multi-configuration generator like Visual Studio?


In the next chapter, we will begin to explore advanced techniques for customizing the build process itself. We'll start by introducing **generator expressions**, the `$<...>` syntax we've encountered a few times already.  These allow us to embed deferred, build-time logic directly into target properties.


</Preview>


</Pw>

User Presets and Customization

CMake Presets - Environment Variables

CMake Presets - Condition

Using environment variables in VS Code

How to use environment variables in CMake?

Deep CMake For Library Authors (CppCon 2019)

Environment variable

Master advanced CMake Presets by learning to use environment variables with the $env{} syntax and conditional visibility with the 'condition' key. Create truly portable presets that adapt to any developer's machine.

CMake Presets Tutorial: Environment Variables and Conditional Presets

Environment Variables in `CMakeLists.txt`

Environment Variables and Conditional Presets

Understanding the Basics

Practical Applications

Common Mistakes

Next Steps

Additional Resources

Assessment Preparation

Managing C++ Projects Using CMake