51Degrees Device Detection C/C++  4.1

A device detection library that is used natively or by 51Degrees products

51Degrees Device Detection API

51Degrees Device Detection

C Documentation and the C++ Documentation.

The 51Degrees device detection API is built on the 51Degrees common API.


Data File

In order to perform device detection, you will need to use a 51Degrees data file. This repository includes a free, 'lite' file in the 'device-detection-data' sub-module that has a significantly reduced set of properties. To obtain a file with a more complete set of device properties see the 51Degrees website. If you want to use the lite file, you will need to install GitLFS.

For Linux:

sudo apt-get install git-lfs
git lfs install

Then, navigate to the device-detection-data directory and execute:

git lfs pull

Fetching sub-modules

This repository has sub-modules that must be fetched. If cloning for the first time, use:

git clone --recurse-submodules https://github.com/51Degrees/device-detection-cxx.git

If you have already cloned the repository and want to fetch the sub modules, use:

git submodule update --init --recursive

If you have downloaded this repository as a zip file then these sub modules need to be downloaded separately as GitHub does not include then in the archive. In particular, note that the zip download will contain links to LFS content, rather than the files themselves. As such, these need to be downloaded individually.

Build tools


You will need either Visual Studio 2019 or the C++ Build Tools installed. If you have Visual Studio Code, you'll still need to install the build tools from the link above.


You will need CMake 3.10 or greater installed to build the project. In addition, you will need a C++ compiler which supports C++11. The compiler will and other build tools will be selected by CMake automatically based on your environment.


Using CMake

To build the make files required to build, open a bash or Visual Studio Developer Command Prompt terminal and run

mkdir build
cd build
cmake ..

Note: on an x64 Windows system, it is neccessary to add -A x64 as CMake will build a Win32 Solution by default.

Then build the whole solution with

cmake --build . --config Release

Libraries are output to the lib/ directory, and executables like examples and tests are output to the bin/ directory.

Using Visual Studio

Calling CMake in an MSVC environment (as described in the Using CMake section) will produce a Visual Studio solution with projects for all libraries, examples, and tests. However, it is preferable to use the dedicated Visual Studio solution in the VisualStudio/ directory.

Build Options

For build options, see Common API


All unit, integration, and performance tests are built using the Google test framework.


CMake automatically pulls in the latest Google Test from GitHub.

Building the project builds multiple test executables to the bin/ directory: HashTests and any common testing included in the common-cxx library.

These can be run by calling


If CMake has been used in an MSVC environment, then the tests will be set up and discoverable in the Visual Studio solution 51DegreesDeviceDetection created by CMake.

Visual Studio

Tests in the Visual Studio solution automatically install the GTest dependency via a NuGet package. However, in order for the tests to show up in the Visual Studio test explorer, the Test Adapter for Google Test extension must be installed.

The VisualStudio solution includes FiftyOne.DeviceDetection.Hash.Tests, which can be run through the standard Visual Studio test runner.

Referencing the API


When building using CMake, static libraries are built in stages. These can be included in an executable just as they are in the examples. If these are included through a CMake file, the dependencies will be resolved automatically. However, if linking another way, all dependencies will need to be included from the lib/ directory. For example, to use the Hash C API, the following static libraries would need to be included:

  • fiftyone-common-c
  • fiftyone-device-detection-c
  • fiftyone-hash-c

and for the Hash C++ API, the following are needed in addition:

  • fiftyone-common-cxx
  • fiftyone-device-detection-cxx
  • fiftyone-hash-cxx

The CMake project also builds a single shared library containing everything. This is named fiftyone-device-detection-complete and can be referenced by any C or C++ project.

Visual Studio

The Visual Studio solution contains static libraries which have all the dependencies set up correctly, so referencing these in a Visual Studio solution should be fairly self explanatory.


There are several examples available, the source files can be found in the examples/ folder. The examples are written in C or CPP.

Visual Studio

All the examples are available to run in the VisualStudio/DeviceDetection.sln solution.

Device Detection Examples

Example Description Language
Getting Started This example shows how to get set up with a Device Detection Cloud aspect engine and begin using it to process User-Agents. C / C++
Match Metrics This example shows how to view metrics associated with the results of processing with a Device Detection aspect engine using the Hash algorithm. C / C++
Meta Data This example shows how to interrogate the meta data associated with the contents of a Device Detection Hash data file. C++
MemHash This example measures the memory usage of the Hash algorithm. C
Offline Processing This example shows how process data for later viewing using a Device Detection Hash data file. C
PerfHash Command line performance evaluation program which takes a file of user agents and returns a performance score measured in detections per second per CPU core. C
ProcHash Command line process which takes a user agent via stdin and return device properties via stdout. C
Reload From File This example illustrates how to reload the data file from the data file on disk without restarting the application. C / C++
Reload From Memory This example illustrates how to reload the data file from a continuous memory space that the data file was read into without restarting the application. C / C++
Strongly Typed This example takes some common User-Agents and returns the value of the IsMobile property as a boolean. C / C++