# KnownLengthArray

VTKExamples/Cxx/Utilities/KnownLengthArray

### Description

This example creates a VTK style float array. This can be easily interchanged with vtkIntArray, vtkDoubleArray, etc.

The terminology is as follows:

- `SetNumberOfComponents()`: sets the number of elements that a tuple in the array will have. See VectorArrayKnownLength for an example with tuples with more than one element.

- `SetNumberOfValues()`: sets the number of tuples the array will have. See UnknownLengthArray for an example where the number of values is not known in advance.

### Code

KnownLengthArray.cxx

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

    int main(int, char *[])
    {
      vtkSmartPointer<vtkFloatArray> distances =
        vtkSmartPointer<vtkFloatArray>::New();
      distances->SetName("Distances");
      distances->SetNumberOfComponents(1);
      distances->SetNumberOfValues(5);

      //set values
      for(vtkIdType i = 0; i < distances->GetNumberOfTuples(); i++)
      {
        float f = (float)i + 0.1;
        distances->SetValue(i, 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 2.8)

    PROJECT(KnownLengthArray)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(KnownLengthArray MACOSX_BUNDLE KnownLengthArray.cxx )

    target_link_libraries(KnownLengthArray ${VTK_LIBRARIES})

### Download and Build KnownLengthArray

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

    cd KnownLengthArray/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:

    ./KnownLengthArray

WINDOWS USERS

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