Tutorial: Install and use packages with CMake
This tutorial shows you how to create a C++ "Hello World" program that uses the fmt
library with CMake and vcpkg. You'll install dependencies, configure, build, and run a simple application.
Prerequisites
Note
For Windows users, Visual Studio's MSVC (Microsoft Visual C++ Compiler) is the required compiler for C++ development.
1 - Set up vcpkg
Clone the repository
The first step is to clone the vcpkg repository from GitHub. The repository contains scripts to acquire the vcpkg executable and a registry of curated open-source libraries maintained by the vcpkg community. To do this, run:
git clone https://github.com/microsoft/vcpkg.git
The vcpkg curated registry is a set of over 2,000 open-source libraries. These libraries have been validated by vcpkg's continuous integration pipelines to work together. While the vcpkg repository does not contain the source code for these libraries, it holds recipes and metadata to build and install them in your system.
Run the bootstrap script
Now that you have cloned the vcpkg repository, navigate to the
vcpkg
directory and execute the bootstrap script:cd vcpkg && bootstrap-vcpkg.bat
cd vcpkg; .\bootstrap-vcpkg.bat
cd vcpkg && ./bootstrap-vcpkg.sh
The bootstrap script performs prerequisite checks and downloads the vcpkg executable.
That's it! vcpkg is set up and ready to use.
2 - Set up the project
Configure the
VCPKG_ROOT
environment variable.export VCPKG_ROOT=/path/to/vcpkg export PATH=$VCPKG_ROOT:$PATH
Note
Setting environment variables using the
export
command only affects the current shell session. To make this change permanent across sessions, add theexport
command to your shell's profile script (e.g.,~/.bashrc
or~/.zshrc
).set "VCPKG_ROOT=C:\path\to\vcpkg" set PATH=%VCPKG_ROOT%;%PATH%
Note
Setting environment variables in this manner only affects the current terminal session. To make these changes permanent across all sessions, set them through the Windows System Environment Variables panel.
$env:VCPKG_ROOT = "C:\path\to\vcpkg" $env:PATH = "$env:VCPKG_ROOT;$env:PATH"
Note
Setting environment variables in this manner only affects the current terminal session. To make these changes permanent across all sessions, set them through the Windows System Environment Variables panel.
Setting
VCPKG_ROOT
tells vcpkg where your vcpkg instance is located. Adding it toPATH
ensures you can run vcpkg commands directly from the shell.Create the project directory.
mkdir helloworld && cd helloworld
3 - Add dependencies and project files
Create the manifest file and add the
fmt
dependency.First, create a manifest file (
vcpkg.json
) in your project's directory by running thevcpkg new
command from within thehelloworld
directory:vcpkg new --application
Next, add the
fmt
dependency:vcpkg add port fmt
Your
vcpkg.json
should look like this:{ "dependencies": [ "fmt" ] }
This is your manifest file. vcpkg reads the manifest file to learn what dependencies to install and integrates with CMake to provide the dependencies required by your project.
The default
vcpkg-configuration.json
file introduces baseline constraints, specifying the minimum versions of dependencies that your project should use. While modifying this file is beyond the scope of this tutorial, it plays a crucial role in defining version constraints for your project's dependencies. Therefore, even though it's not strictly necessary for this tutorial, it's a good practice to addvcpkg-configuration.json
to your source control to ensure version consistency across different development environments.Create the project files.
Create the
CMakeLists.txt
file with the following content:cmake_minimum_required(VERSION 3.10) project(HelloWorld) find_package(fmt CONFIG REQUIRED) add_executable(HelloWorld main.cpp) target_link_libraries(HelloWorld PRIVATE fmt::fmt)
Now, let's break down what each line in the
CMakeLists.txt
file does:cmake_minimum_required(VERSION 3.10)
: Specifies that the minimum version of CMake required to build the project is 3.10. If the version of CMake installed on your system is lower than this, an error will be generated.project(HelloWorld)
: Sets the name of the project to "HelloWorld."find_package(fmt CONFIG REQUIRED)
: Looks for thefmt
library using its CMake configuration file. TheREQUIRED
keyword ensures that an error is generated if the package is not found.add_executable(HelloWorld main.cpp)
: Adds an executable target named "HelloWorld," built from the source filemain.cpp
.target_link_libraries(HelloWorld PRIVATE fmt::fmt)
: Specifies that theHelloWorld
executable should link against thefmt
library. ThePRIVATE
keyword indicates thatfmt
is only needed for buildingHelloWorld
and should not propagate to other dependent projects.
Create the
main.cpp
file with the following content:#include <fmt/core.h> int main() { fmt::print("Hello World!\n"); return 0; }
In this
main.cpp
file, the<fmt/core.h>
header is included for using thefmt
library. Themain()
function then callsfmt::print()
to output the "Hello World!" message to the console.
4 - Build and run the project
Run CMake configuration
To allow the CMake project system to recognize C++ libraries provided by vcpkg, you'll need to provide the
vcpkg.cmake
toolchain file. To automate this, create aCMakePresets.json
file in the "helloworld" directory with the following content:{ "version": 2, "configurePresets": [ { "name": "default", "generator": "Ninja", "binaryDir": "${sourceDir}/build", "cacheVariables": { "CMAKE_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake" } } ] }
This
CMakePresets.json
file contains a single "default" preset for CMake and sets theCMAKE_TOOLCHAIN_FILE
variable. TheCMAKE_TOOLCHAIN_FILE
allows the CMake project system to recognize C++ libraries provided by vcpkg. Adding theCMakePresets.json
automates the process of specifying the toolchain when running CMake.Configure the build using CMake:
cmake --preset=default
Build the project
Run:
cmake --build build
Run the application
Finally, run the executable to see your application in action:
./build/HelloWorld Hello World!
.\build\HelloWorld.exe Hello World!