Tutorial: Install and use packages with CMake in Visual Studio

This tutorial shows you how to create a C++ "Hello World" program that uses the fmt library with CMake, vcpkg and Visual Studio. You'll install dependencies, configure, build, and run a simple application.

Prerequisites

Visual Studio with C++ development workload and CMake component
Git

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:

Powershell or Command Prompt:

cd vcpkg && bootstrap-vcpkg.bat

cd vcpkg; .\bootstrap-vcpkg.bat

Bash:

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 Visual Studio project

Create the Visual Studio project
- Create a new project in Visual Studio using the "CMake Project" template
- Name your project "helloworld"
- Check the box for "Place solution and project in the same directory."
- Click the "Create" button
Configure the VCPKG_ROOT environment variable.
```
Open the built-in Developer PowerShell window in Visual Studio.
```
Run the following commands:
```
$env:VCPKG_ROOT = "C:\path\to\vcpkg"
$env:PATH = "$env:VCPKG_ROOT;$env:PATH"
```
Open the Developer command prompt in Visual Studio.

Run the following commands:
```
set VCPKG_ROOT="C:\path\to\vcpkg"
set PATH=%VCPKG_ROOT%;%PATH%
```
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 helps Visual Studio locate your vcpkg instance. Adding it to PATH ensures you can run vcpkg commands directly from the shell.
Generate a manifest file and add dependencies.

Run the following command to create a vcpkg manifest file (vcpkg.json):
```
vcpkg new --application
```
The vcpkg new command adds a vcpkg.json file and a vcpkg-configuration.json file in the project's directory.

Add the fmt package as a dependency:
```
vcpkg add port fmt
```
Your vcpkg.json should now contain:
```
{
    "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 generated vcpkg-configuration.json file introduces a baseline that places minimum version constraints on the project's dependencies. Modifying this file is beyond the scope of this tutorial. While not applicable in this tutorial, it's a good practice to keep the vcpkg-configuration.json file under source control to ensure version consistency across different development environments.

3 - Set up the project files

Modify the helloworld.cpp file.

Replace the content of helloworld.cpp with the following code:
```
#include <fmt/core.h>

int main()
{
  fmt::print("Hello World!\n");
  return 0;
}
```
This source file includes the <fmt/core.h> header which is part of the fmt library. The main() function calls fmt::print() to output the "Hello World!" message to the console.
Configure the CMakePresets.json file.
- Rename the CMakePresets.json file to CMakeUserPresets.json
- Update its contents as shown below. Replace <VCPKG_ROOT> with the path to your vcpkg directory.
```
{
  "version": 2,
  "configurePresets": [
    {
      "name": "default",
      "generator": "Ninja",
      "binaryDir": "${sourceDir}/build",
      "cacheVariables": {
        "CMAKE_TOOLCHAIN_FILE": "<VCPKG_ROOT>/scripts/buildsystems/vcpkg.cmake"
      }
    }
  ]
}
```
- Since this file includes a hardcoded absolute path, it is recommended that you don't keep this file under source control. If you're using Git, add CMakeUserPresets.json to your .gitignore file.
The CMakeUserPresets.json file contains a single preset named "default", this preset sets the CMAKE_TOOLCHAIN_FILE to use vcpkg's CMake toolchain file. This lets vcpkg provide packages to CMake when you configure and build the project. Read the vcpkg CMake integration documentation to learn more.
Edit the CMakeLists.txt file.

Replace the contents of the CMakeLists.txt file with the following code:
```
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, the build fails.
- project(HelloWorld): Sets the name of the project to "HelloWorld."
- find_package(fmt CONFIG REQUIRED): Looks for the fmt library using its CMake configuration file. The REQUIRED keyword ensures that an error is generated if the package is not found.
- add_executable(HelloWorld helloworld.cpp): Adds an executable target named "HelloWorld," built from the source file helloworld.cpp.
- target_link_libraries(HelloWorld PRIVATE fmt::fmt): Specifies that the HelloWorld executable should link against the fmt library. The PRIVATE keyword indicates that fmt is only needed for building HelloWorld and should not propagate to other dependent projects.

4 - Build and run the project

Build the project.

Press Ctrl+Shift+B to build the project in Visual Studio.
Run the application.

Next steps

To learn more about vcpkg.json, see our reference documentation:

nero-dv/vcpkg_Visual-Studio-init.md