ucpp is a C preprocessor. It is designed to be quick and light, but still fully compliant to the ISO standard 9899:1999, also known as C99. ucpp can be compiled as a stand-alone program or linked to some other code; in the latter case, ucpp will output tokens, one at a time, on demand, as an integrated lexer. ucpp operates in two modes: in lexer mode, ucpp is linked to some other code and outputs a stream of tokens where each call to the lex() function will yield one token; in non-lexer mode, ucpp preprocesses text and outputs the resulting text to a file descriptor. If linked to some other code, the cpp() function must be called repeatedly, otherwise ucpp is a stand-alone binary.
cauxp provides additional preprocessing directives designed to help programmers create easily-maintained code. It allows multiline macros without the annoyance of line continuation markers and can do automatic bracketing of macro parameters. It also provides methods for defining groups of related constants and flags. You can also invoke other processors from within cauxp.