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# UnknownLengthArray

VTKEx/Cxx/Utilities/UnknownLengthArray

### Description

The only difference between this example and the KnownLengthArray example is that `SetNumberOfValues()` is not called, and `SetValue()` is replaced by `InsertNextValue()`.

Other languages

See (Java)

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

UnknownLengthArray.cxx

    #include <vtkSmartPointer.h>
    #include <vtkFloatArray.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkFloatArray> distances =
        vtkSmartPointer<vtkFloatArray>::New();
      distances->SetName("Distances");
      distances->SetNumberOfComponents(1);

      //set values
      for(vtkIdType i = 0; i < 5; i++)
      {
        float f = (float)i + 0.1;
        //this will allocate memory as necessary
        distances->InsertNextValue(f);
      }

      //get values
      for(vtkIdType i = 0; i < distances->GetNumberOfTuples(); i++)
      {
        float f = distances->GetValue(i);
        std::cout << f << std::endl;
      }

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(UnknownLengthArray)

    find_package(VTK COMPONENTS
      vtkvtkCommonCore QUIET)
    if (NOT VTK_FOUND)
      message("Skipping UnknownLengthArray: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(UnknownLengthArray MACOSX_BUNDLE UnknownLengthArray.cxx )
      target_link_libraries(UnknownLengthArray PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(UnknownLengthArray MACOSX_BUNDLE UnknownLengthArray.cxx )
      target_link_libraries(UnknownLengthArray PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS UnknownLengthArray
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build UnknownLengthArray

Click here to download UnknownLengthArray and its CMakeLists.txt file. Once the tarball UnknownLengthArray.tar has been downloaded and extracted,

    cd UnknownLengthArray/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./UnknownLengthArray

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.