MLC++: A Machine Learning Library in C++ Ron Kohavi George John Richard Long David Manley Karl Pfleger Computer Science Department Stanford University Stanford, CA 94305 mlc@CS.Stanford.EDU We present MLC++, a library of C++ classes and tools for supervised Machine Learning. While MLC++ provides general learning algorithms that can be used by end users, the main objective is to provide researchers and experts with a wide variety of tools that can accelerate algorithm development, increase software reliability, provide comparison tools, and display information visually. More than just a collection of existing algorithms, MLC++ is an attempt to extract commonalities of algorithms and decompose them for a unified view that is simple, coherent, and extensible. In this paper we discuss the problems MLC++ aims to solve, the design of MLC++, and the current functionality. Citation: Ron Kohavi, George John, Richard Long, David Manley, and Karl Pfleger. MLC++: a machine learning library in C++. In _Sixth National Conference on Tools with Artificial Intelligence_, pages 740--743. IEEE Press, 1994.