1.14 Values available to the user

This section summarizes the various values available to the user in the rule actions.

• `char *yytext' holds the text of the current token. It may be modified but not lengthened (you cannot append characters to the end). If the special directive `%array' appears in the first section of the scanner description, then yytext is instead declared `char yytext[YYLMAX]', where YYLMAX is a macro definition that you can redefine in the first section if you don't like the default value (generally 8KB). Using `%array' results in somewhat slower scanners, but the value of yytext becomes immune to calls to `input()' and `unput()', which potentially destroy its value when yytext is a character pointer. The opposite of `%array' is `%pointer', which is the default. You cannot use `%array' when generating C++ scanner classes (the `-+' flag).
• `int yyleng' holds the length of the current token.
• `FILE *yyin' is the file which by default flex reads from. It may be redefined but doing so only makes sense before scanning begins or after an EOF has been encountered. Changing it in the midst of scanning will have unexpected results since flex buffers its input; use `yyrestart()' instead. Once scanning terminates because an end-of-file has been seen, you can assign yyin at the new input file and then call the scanner again to continue scanning.
• `void yyrestart( FILE *new_file )' may be called to point yyin at the new input file. The switch-over to the new file is immediate (any previously buffered-up input is lost). Note that calling `yyrestart()' with yyin as an argument thus throws away the current input buffer and continues scanning the same input file.
• `FILE *yyout' is the file to which `ECHO' actions are done. It can be reassigned by the user.
• YY_CURRENT_BUFFER returns a YY_BUFFER_STATE handle to the current buffer.
• YY_START returns an integer value corresponding to the current start condition. You can subsequently use this value with BEGIN to return to that start condition.

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