Trying to build shared library by using third party libraries, cmake and vcpkg

3 min read 19-09-2024

Trying to build shared library by using third party libraries, cmake and vcpkg

Creating a shared library in C++ can be a daunting task, especially when integrating third-party libraries. This article will guide you through building a shared library using CMake and vcpkg, simplifying the process and making it more efficient.

Problem Scenario

You're attempting to build a shared library that relies on third-party libraries. The goal is to use CMake as your build system and manage the dependencies with vcpkg, a popular package manager for C++. Below is a basic code snippet showing how you might set up a CMake project for a shared library without any package management:

cmake_minimum_required(VERSION 3.10)

project(MySharedLibrary)

add_library(MySharedLibrary SHARED src/mylibrary.cpp)

target_include_directories(MySharedLibrary PUBLIC include)

Understanding the Solution

To effectively build a shared library that utilizes third-party libraries, you need to incorporate vcpkg for easy dependency management. vcpkg allows you to install and use libraries such as Boost, OpenCV, and more in a seamless manner.

Step-by-Step Guide

Install vcpkg: If you haven't already, you can set up vcpkg by cloning its repository and running the bootstrap script.
```
git clone https://github.com/microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
```
Install Dependencies: Use vcpkg to install any third-party libraries needed for your project. For example, if you need Boost, you can install it using:
```
./vcpkg/vcpkg install boost
```

Integrate vcpkg with CMake: Modify your CMakeLists.txt file to find and link the installed libraries.

Here is an updated version of your CMakeLists.txt that integrates vcpkg:

cmake_minimum_required(VERSION 3.10)

project(MySharedLibrary)

# Set the CMake toolchain file for vcpkg
set(CMAKE_TOOLCHAIN_FILE "path/to/vcpkg/scripts/buildsystems/vcpkg.cmake" CACHE STRING "Vcpkg toolchain file")

find_package(Boost REQUIRED)

add_library(MySharedLibrary SHARED src/mylibrary.cpp)

target_include_directories(MySharedLibrary PUBLIC include ${Boost_INCLUDE_DIRS})
target_link_libraries(MySharedLibrary PRIVATE ${Boost_LIBRARIES})

Replace "path/to/vcpkg" with the actual path where you cloned vcpkg.

Additional Explanations

CMake Toolchain File: The line that sets the CMAKE_TOOLCHAIN_FILE is crucial. It tells CMake to use the vcpkg toolchain, allowing it to know where to find the installed libraries.
find_package(): This command searches for the Boost package and includes it in your build, ensuring that the necessary headers and libraries are available.
target_link_libraries(): This is where you specify which libraries your shared library will link against. In this case, Boost libraries are linked to MySharedLibrary.

Practical Example

Let’s assume you are creating a shared library for a simple math operations module that uses the Boost library for complex number calculations.

Install the Boost library via vcpkg.

Create your mylibrary.cpp with the following content:

#include <boost/math/complex.hpp>

extern "C" {
    void complexOperations() {
        boost::math::complex<double> c(1.0, 2.0);
        // Perform operations with complex numbers
    }
}

Build your library:
```
mkdir build
cd build
cmake ..
make
```
You now have a shared library that integrates Boost through vcpkg, making dependency management straightforward and efficient.

Conclusion

Building a shared library using CMake and vcpkg streamlines the process of managing third-party libraries in C++. By following the steps outlined above, you can create powerful and reusable components for your C++ applications.

Additional Resources

By utilizing CMake and vcpkg effectively, you can enhance your C++ development experience and ensure your projects remain maintainable and scalable. Happy coding!