What is the difference between Flex/Lex and Yacc/Bison?

Question

What is the difference between Flex & Lex and Yacc & Bison. I searched the Internet wildly and I didn\'t find any solid answer.

Can I install pure Lex and Yacc o

Answer 1

YACC is available under open source licenses from both Plan 9 and Open Solaris. Also, there is also Berkeley YACC, which is compatible with the original YACC, but does not share source code. Berkeley YACC can be found on any of the open source BSD operating systems.