Standard C++ does not provide mechanisms for working with assertions in the spirit of design by contract (DBC) as proposed by Meyer. We earlier developed a set of techniques and tools facilitating the prototyping of object-oriented architectures based on the idea of design by contract.As it is crucial for us to support evolutionary prototyping, we need to provide mechanisms to automatically transform the classes and assertions specified in our prototyping environment to C++. Therefore we developed a system that automatically transforms classes and assertions of our prototyping system to C++. As a side effect our environment provides general mechanisms for realizing design by contract for the programming language C++.