# FunctionParser

VTKExamples/Cxx/Utilities/FunctionParser

### Description

This example shows how to substitute values and evaluate a string such as "a+b".

### Code

FunctionParser.cxx

    #include <vtkSmartPointer.h>
    #include <vtkFunctionParser.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkFunctionParser> functionParser =
          vtkSmartPointer<vtkFunctionParser>::New();
      functionParser->SetFunction("a+b");

      functionParser->SetScalarVariableValue( "a", 2);
      functionParser->SetScalarVariableValue( "b", 3);

      double result = functionParser->GetScalarResult();

      std::cout << "result: " << result << std::endl;

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(FunctionParser)

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

    add_executable(FunctionParser MACOSX_BUNDLE FunctionParser.cxx)

    target_link_libraries(FunctionParser ${VTK_LIBRARIES})

### Download and Build FunctionParser

Danger

The generation of tar files has not been ported to the new VTKExamples. Some tarballs may be missing or out-of-date.

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

    cd FunctionParser/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:

    ./FunctionParser

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