What is the difference between YYLEX_PARAM and YY_DECL?

YYLEX_PARAM is not a flex symbol. It is for Bison. It tells Bison to pass extra params when it calls yylex() from the parser.

YY_DECL is the Flex declaration of yylex. The default is similar to this:

#define int yy_lex ()

This document was generated by Wolfram Kahl on September, 9 2006 using texi2html 1.76.