LANCE comprises a frontend for full ANSI C (C89 language version). It requires a separate C preprocessor, though, and standard header files and libraries are NOT included. Normally, these components are reused from the GNU C compiler.

LANCE's ANSI C frontend source code has been automatically generated by means of the attribute grammar compiling system OX (available from: ftp://ftp.cs.iastate.edu/pub/ox/). OX reads an attribute grammar and generates lex and yacc source files. The use of generated C frontend code significantly reduces the coding effort and improves reliability.

The C frontend is called via the "compile" shell command. It translates each C source file into a separate IR file.