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macosflex-lexer

Using Flex (the lexical analizer) on OS X

I've got a file, test.lex, which I run through as

$ flex test.lex

That gives me lex.yy.c, which I try to compile with:

$ gcc lex.yy.c -lfl

This gives me the error ld: library not found for -lfl. I know the Flex specification is correct and lex.yy.c compiles fine on a Linux machine. Any suggestions?

Edit: I'm using the flex supplied by Apple.

Solution

  • Some systems make libfl a separate package from flex, as it is rarely needed. The libfl library just contains two functions:

    int main() {
    while (yylex());
    return 0;
}

int yywrap() {
    return 1;
}

    Normally you'll want your own main function rather than the one from libfl, and defining yywrap yourself is trivial. Alternately, you can use %option noyywrap and not need it at all.

    In your case, try just getting rid of the -lfl option. If you get an error about yywrap, add
    %option noyywrap to the first section of your test.lex file.