CBack: A Simple Tool for Backtrack Programming in C. Backtrack programming is such a powerful technique for problem solving that a number of languages, especially in the area of artificial intelligence, have built-in facilities for backtrack programming. CBack is a simple, but general tool for backtrack programming in the programming language C. In addition to the usual depth-first search strategy, CBack provides for the more general heuristic best-first search strategy. The source code, shown in its full length, is entirely written in ANSI C and highly portable across diverse computer architectures and C compilers.