example.rst

Code Example

The following example shows a small hello word example written with alpaka that can be run on different processors.

.. literalinclude:: ../../../example/helloWorld/src/helloWorld.cpp
   :language: C++
   :caption: helloWorld.cpp

Use alpaka in your project

We recommend to use CMake for integrating alpaka into your own project. There are two possible methods.

Use alpaka via find_package

The find_package method requires alpaka to be :doc:`installed </basic/install>` in a location where CMake can find it.

Hint

If you do not install alpaka in a default path such as /usr/local/ you have to set the CMake argument -Dalpaka_ROOT=/path/to/alpaka/install.

The following example shows a minimal example of a CMakeLists.txt that uses alpaka:

cmake_minimum_required(VERSION 3.18)

set(_TARGET_NAME myProject)
project(${_TARGET_NAME})

find_package(alpaka REQUIRED)

alpaka_add_executable(${_TARGET_NAME} helloWorld.cpp)
target_link_libraries(
  ${_TARGET_NAME}
  PUBLIC alpaka::alpaka)

In the CMake configuration phase of the project, you must activate the accelerator you want to use:

cd <path/to/the/project/root>
mkdir build && cd build
# enable the CUDA accelerator
cmake .. -Dalpaka_ACC_GPU_CUDA_ENABLE=ON
# compile and link
cmake --build .
# execute application
./myProject

A complete list of CMake flags for the accelerator can be found :doc:`here </advanced/cmake>`.

If the configuration was successful and CMake found the CUDA SDK, the C++ template accelerator type alpaka::acc::AccGpuCudaRt is available.

Use alpaka via add_subdirectory

The add_subdirectory method does not require alpaka to be installed. Instead, the alpaka project folder must be part of your project hierarchy. The following example expects alpaka to be found in the project_path/thirdParty/alpaka:

cmake_minimum_required(VERSION 3.18)

set(_TARGET_NAME myProject)
project(${_TARGET_NAME})

add_subdirectory(thirdParty/alpaka)

alpaka_add_executable(${_TARGET_NAME} helloWorld.cpp)
target_link_libraries(
  ${_TARGET_NAME}
  PUBLIC alpaka::alpaka)

The CMake configure and build commands are the same as for the find_package approach.