---
metadata:
  - name: generator
    content: Diplodoc Platform v5.50.3
alternate:
  - https://catboost.ai/docs/en/concepts/c-plus-plus-api_dynamic-c-pluplus-wrapper.md
---
> **Documentation Index:** Fetch the complete configuration index at https://catboost.ai/docs/en/llms.txt

# Evaluation library

This is the fastest way to evaluate a model. The library provides a [C API](#c-api) and a simple [C++ wrapper API](#c-plus-plus-wrapper). The C API interface can be accessed from any programming language.

## Download

Prebuilt shared library artifacts are available.

<!-- source: en/_includes/work_src/reusage-cli/releases-page.md -->
An up-to-date list of available CatBoost releases and the corresponding binaries for different operating systems is available in the **Download** section of the [releases](https://github.com/catboost/catboost/releases) page on GitHub.

|Operating system|CPU architectures|GPU support using [CUDA](https://developer.nvidia.com/cuda-zone)|
|--------|-----------------|------------|
| macOS (versions currently supported by Apple) | x86_64 and arm64 |no|
| Linux (compatible with [manylinux2014 platform tag](https://peps.python.org/pep-0599/) ) | x86_64 and aarch64 |yes|
| Windows (versions 10, 11, Server 2022, Server 2025) | x86_64 |yes|

{% note info %}

Release binaries for x86_64 CPU architectures are built with SIMD extensions SSE2, SSE3, SSSE3, SSE4 enabled. If you need to run CatBoost on older CPUs that do not support these instruction sets [build CatBoost artifacts yourself](https://catboost.ai/docs/en/concepts/build-from-source.md)

{% endnote %}
<!-- endsource: en/_includes/work_src/reusage-cli/releases-page.md -->

{% note info %}

<!-- source: en/_includes/work_src/reusage-installation/gpu-support-from-the-box__p.md -->
This version has CUDA-enabled GPU support out-of-the-box on Linux and Windows.
<!-- endsource: en/_includes/work_src/reusage-installation/gpu-support-from-the-box__p.md -->

<!-- source: en/_includes/work_src/reusage-code-examples/compute-capability-requirements.md -->
As of CatBoost 1.2.10, devices with CUDA compute capability >= 3.5 are supported in released packages.

All necessary CUDA libraries are statically linked in the released Linux and Windows binaries, the only installation necessary is the appropriate version of the CUDA driver.
<!-- endsource: en/_includes/work_src/reusage-code-examples/compute-capability-requirements.md -->

Inference on CUDA-enabled GPUs requires NVIDIA Driver of version 450.80.02 or higher.

{% endnote %}

|Operating system|Files|
|--|-----|
|Linux|`libcatboostmodel-linux-{cpu_arch}-{release_version}.so`|
|macOS|`libcatboostmodel-darwin-universal2-{release_version}.dylib`|
|Windows|`catboostmodel-windows-{cpu_arch}-{release_version}.lib` and `catboostmodel-windows-{cpu_arch}-{release_version}.dll`|

## Build from source {#build}

{% note warning %}

<!-- source: en/_includes/work_src/reusage-installation/ya-make-to-cmake-switch.md -->
CatBoost uses [CMake](https://cmake.org/)-based build process since [this commit](https://github.com/catboost/catboost/commit/c5c642ca0b8e093336d0229ac4b14c78db3915bb). Previously `Ya Make` (Yandex's build system) had been used.
<!-- endsource: en/_includes/work_src/reusage-installation/ya-make-to-cmake-switch.md -->

Select the appropriate build method below accordingly.

{% endnote %}

### Source code

<!-- source: en/_includes/work_src/reusage-installation/get-source-code-from-github.md -->
CatBoost source code is stored as a [Git](https://git-scm.com/) repository on GitHub at <https://github.com/catboost/catboost/>. You can obtain a local copy of this Git repository by running the following command from a command line interpreter (you need to have Git command line tools installed):

    git clone https://github.com/catboost/catboost.git
<!-- endsource: en/_includes/work_src/reusage-installation/get-source-code-from-github.md -->

### Build using CMake  {#cmake}

{% list tabs %}

- Shared library

    Build `catboostmodel` target.

    See [Build native artifacts](https://catboost.ai/docs/en/installation/build-native-artifacts.md).

    Built artifacts will be in `$CMAKE_BINARY_DIR/catboost/libs/model_interface`:

    <!-- source: en/_includes/work_src/reusage-installation/build-model-interface-shared-artifacts.md -->
    |OS|Files|
    |--|-----|
    |Linux|`libcatboostmodel.so`|
    |macOS|`libcatboostmodel.dylib`|
    |Windows|`catboostmodel.lib` and `catboostmodel.dll`|
    <!-- endsource: en/_includes/work_src/reusage-installation/build-model-interface-shared-artifacts.md -->

- Static library

    Build `catboostmodel_static` target.

    See [Build native artifacts](https://catboost.ai/docs/en/installation/build-native-artifacts.md).

    Built library will consist of two parts:
        - `global` part. This part contains symbols that require forced initialization.
        - non-`global` part. All other symbols.

    Built artifacts will be in `$CMAKE_BINARY_DIR/catboost/libs/model_interface/static`:

    |OS|Files|
    |--|-----|
    |Linux or macOS|`libcatboostmodel_static.a`, `libcatboostmodel_static.global.a`|
    |Windows|`catboostmodel_static.lib`, `catboostmodel_static.global.lib`|

{% endlist %}

### Build using Ya Make  {#ya-make}

1. [Setup build environment](https://catboost.ai/docs/en/installation/build-environment-setup-for-ya-make.md)

1. Open the `catboost` directory from the local copy of the CatBoost repository.

1. Run the following command:

    {% list tabs %}

    - Shared library

        ```
        ./ya make -r [optional parameters] catboost/libs/model_interface
        ```

        The output directory `catboost/libs/model_interface` will contain:

        <!-- source: en/_includes/work_src/reusage-installation/build-model-interface-shared-artifacts.md -->
        |OS|Files|
        |--|-----|
        |Linux|`libcatboostmodel.so`|
        |macOS|`libcatboostmodel.dylib`|
        |Windows|`catboostmodel.lib` and `catboostmodel.dll`|
        <!-- endsource: en/_includes/work_src/reusage-installation/build-model-interface-shared-artifacts.md -->

    - Static library (only for Linux and macOS)

        ```
        ./ya make -r [optional parameters] catboost/libs/model_interface/static
        ```

        The output directory `catboost/libs/model_interface/static` will contain a pair of artifacts:

        <!-- source: en/_includes/work_src/reusage-installation/build-model-interface-static-old-artifacts.md -->
        - `liblibcatboostmodel.o`. This part contains symbols that require forced initialization.
        - `libcatboostmodel.a`. This part contains all other symbols.
        <!-- endsource: en/_includes/work_src/reusage-installation/build-model-interface-static-old-artifacts.md -->

    {% endlist %}

    Useful parameters:

    Parameter | Description
    ----- | -----
    `-DCUDA_ROOT` | The path to CUDA. This parameter is required to support training on GPU.
    `-DHAVE_CUDA=no` | Disable CUDA support. This speeds up compilation.<br/><br/>By default, the package is built with CUDA support if CUDA Toolkit is installed.

### Build using Make (Linux-only)  {#make}

{% note warning %}

This approach will work only for versions prior to [this commit](https://github.com/catboost/catboost/commit/c5c642ca0b8e093336d0229ac4b14c78db3915bb).

For newer versions use [Build with CMake](#cmake)

{% endnote %}

Choose the preferred way to use the evaluation library and compile it accordingly:

{% list tabs %}

- Shared library

    ```bash
    export CXX=/path/to/clang++
    export CC=/path/to/clang

    make -f make/model_interface.CLANG50-LINUX-X86_64.makefile
    ```

    The output directory `catboost/libs/model_interface` will contain `libcatboostmodel.so`.

- Static library

    ```bash
    export CXX=/path/to/clang++
    export CC=/path/to/clang

    make -f make/model_interface_static.CLANG50-LINUX-X86_64.makefile
    ```

    The output directory `catboost/libs/model_interface/static` will contain a pair of artifacts:

    <!-- source: en/_includes/work_src/reusage-installation/build-model-interface-static-old-artifacts.md -->
    - `liblibcatboostmodel.o`. This part contains symbols that require forced initialization.
    - `libcatboostmodel.a`. This part contains all other symbols.
    <!-- endsource: en/_includes/work_src/reusage-installation/build-model-interface-static-old-artifacts.md -->

{% endlist %}

## Usage

The CatBoost model can be loaded from a file or initialized from the buffer memory.

### C API {#c-api}

Perform the following steps to use this API:

1. Use the methods from the `c_api.h` file (refer to the [doxygen-style documentation](https://github.com/catboost/catboost/blob/master/catboost/libs/model_interface/c_api.h) for details).

    Sample C code without include statements:

    ```c
    float floatFeatures[100];
    char* catFeatures[2] = {"1", "2"};
    double result[1];
    ModelCalcerHandle modelHandle;
    modelHandle = ModelCalcerCreate();
    if (!LoadFullModelFromFile(modelHandle, "model.cbm")) {
        printf("LoadFullModelFromFile error message: %s\n", GetErrorString());
    }
    if (!CalcModelPrediction(
            modelHandle,
            1,
            &floatFeatures, 100,
            &catFeatures, 2,
            &result, 1
        )) {
        printf("CalcModelPrediction error message: %s\n", GetErrorString());
    }
    ModelCalcerDelete(modelHandle);
    ```

1. Add the required libraries to the linking command.

    Linker is often invoked through the compiler call, examples below assume that.

    {% list tabs %}

    - Shared library

        - Linux or macOS

            Example:

            ```
            clang++ <your sources and options> -L<path_to_dir_with_libcatboostmodel> -lcatboostmodel
            ```

        - Windows

            Example:

            ```
            cl.exe <your sources and options> /link <path_to_dir_with_libcatboostmodel>\catboostmodel.lib
            ```

        The shared library must be accessible from the dynamic library loader search path. See your operating system documentation for the details.

    - Static library built using CMake

        Add both `global` and non-`global` parts to the linker input. `global` part requires passing special platform-specific flags to force the required initialization of symbols.

        See per-platform examples below:

        - Linux

            On Linux additional libraries `libdl` and `libpthread` have to be added to the linker input as well.

            ```
            clang++ <your sources and options> -Wl,--whole-archive <catboost_lib_dir>/libcatboostmodel_static.global.a -Wl,--no-whole-archive <catboost_lib_dir>/libcatboostmodel_static.a -lpthread -ldl
            ```

        - macOS

            ```
            clang++ <your sources and options> <catboost_lib_dir>/libcatboostmodel_static.a
            -Wl,-force_load,<catboost_lib_dir>/libcatboostmodel_static.global.a
            ```

       - Windows

            When using `c_api.h` with the static library the additional define `CATBOOST_API_STATIC_LIB` is required.

            ```
            cl.exe <your sources and options> /DCATBOOST_API_STATIC_LIB /link /WHOLEARCHIVE:<catboost_lib_dir>\catboostmodel_static.global.lib <catboost_lib_dir>\catboostmodel_static.lib
            ```

    - Static library built using Ya Make or Make (Linux or macOS only)

        Add both `liblibcatboostmodel.o` and  `libcatboostmodel.a` to the linker input.

        On Linux additional libraries `libdl` and `libpthread` have to be added to the linker input as well.

        Example:

        ```
        clang++ <your sources and options> liblibcatboostmodel.o libcatboostmodel.a -ldl -lpthread
        ```

    {% endlist %}

### C++ wrapper API {#c-plus-plus-wrapper}

A C++ wrapper for the C API interface is also available.

{% note info %}

The C++ wrapper code requires C++11 or later.

{% endnote %}

Refer to the [wrapped_calcer.h](https://github.com/catboost/catboost/blob/master/catboost/libs/model_interface/wrapped_calcer.h) file and the sample [CMake project](https://github.com/catboost/catboost/blob/master/catboost/libs/model_interface/cmake_example/CMakeLists.txt) in the CatBoost repository for more details.

Usage example:
```cpp
ModelCalcerWrapper calcer("model.cbm");
std::vector<float> floatFeatures(100);
std::vector<std::string> catFeatures = {"one", "two", "three"};
std::cout << calcer.Calc(floatFeatures, catFeatures) << std::endl;
```

`ModelCalcerWrapper` also has a constructor to read data from the memory buffer.

### Related information

[Source code and a CMake usage example](https://github.com/catboost/catboost/tree/master/catboost/libs/model_interface/cmake_example)