A neural network is a connected collection of neurons (that is, a class that simulates a biological neuron) that can be trained for certain purposes.

Freely downloadable C++ neural networks

From my favorite (top) to my least favorite. This list is incomplete and will remain incomplete.

Shark: my personal favorite machine learning network, because it suits my needs
Flood: the neural network implementation I used when using C++ Builder 6.0. Downsides are const-incorrectness, the use of STL functions without 'std::' in front of it (a simple replace command fixes this, though), the use of handcrafted classes (for example Flood::Vector, instead of std::vector), dirty C-style casts and few documentation. Don't mind me nitpicking: because I use it with much pleasure, I know this one best!
FANN: programmed in C, I found it too hard to use for my own needs.
http://www.bedaux.net/nnet: takes boolians as input and produces boolians as output.
http://www.codeproject.com/cpp/MLP.asp: good code if you like the way Visual C++ handles its GUI
http://sourceforge.net/project/showfiles.php?group_id=10202&package_id=10051&release_id=10643: Average implementation relying heavily on plain pointers
http://members.tripod.com/~zerkpage/backprop.txt fair code which is easy to read, but uses many global pointers
http://sourceforge.net/projects/nn-utility: acceptable source code, except for use of pointers-to-pointers-to-pointers, class names in UPPERCASE
http://www.paraschopra.com/sourcecode/index.php: example how NOT to program: use of macro's, explicit write of void as a function argument, inconsistent indentation, etc...

Untested:

Annie (http://annie.sourceforge.net)

Proposed neural network architecture


template <class Neuron>

struct NeuralNetwork

{

  NeuralNetwork(

    const int nInputs  = 0, 

    const int nHidden  = 0, 

    const int nOutputs = 0); 



  //If the propagation of a neuron does not change its state,

  //NeuralNet::Propagate is a const method

  //Note: this constness must be determined by templates

  const std::vector<double> Propagate(const std::vector<double>& inputs);

  const std::vector<double> Propagate(const std::vector<double>& inputs) const;





  //When a desired input is known, let this backpropagate

  void BackPropagate(const std::vector<double>& desiredOutputs)



  private:

  //The NeuralNetwork is implemented as a boost::graph of Neurons

  boost::graph<Neuron> m_n;

};





//Neuron is an abstract base class

struct Neuron

{

  //Note: this constness must be determined by templates

  double Propagate(const double input) = 0;

  double Propagate(const double input) const = 0;

};

External links

WikiPedia page on neural networks

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

(C++) Neural network

Freely downloadable C++ neural networks

Proposed neural network architecture

External links