c++ - Flex lexer output modification -

how can use flex lexer in c++ , modify token's yytext value? lets say, have rule this:

"/*"    {         char c;         while(true)             {             c = yyinput();             if(c == '\n')                 ++mylineno;              if (c==eof){                 yyerror( "eof occured while processing comment" );                 break;             }             else if(c == '*')                 {                 if((c = yyinput()) == '/'){                     return(tokens::comment);}                 else                     unput(c);                 }             }         } 

and want token tokens::comment value of comment between /* , */. (the bove solution gives "/*" value.

additional, important tracking line number, i'm looking solution supporting it.

edit of course can modify yytext , yyleng values (like yytext+=1; yyleng-=1, still cannot solve above problem)

i still think start conditions right answer.

%x c_comment char *str = null; void addtostring(char *data) {     if(!str)     {          str = strdup(data);     }     else     {         /* handle string concatenation */     } }  "/*"                       { begin(c_comment); } <c_comment>([^*\n\r]|(\*+([^*/\n\r])))*    { addtostring(yytext); } <c_comment>[\n\r]          { /* handle tracking, add string if desired */ } <c_comment>"*/"            { begin(initial); } 

i used following references:
http://ostermiller.org/findcomment.html
https://stackoverflow.com/a/2130124/1003855

you should able use similar regular expression handle strings.