I am using bison+flex to parse file. On error yyerror() is invoked. How can I get the line number or string that is violating the rules, to print it with the error message?
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I am using bison+flex to parse file. On error yyerror() is invoked. How can I get the line number or string that is violating the rules, to print it with the error message?
Line number is easy:
yylinenois the line number. Specify%option yylinenoat the top of your .l file.Well, almost easy. Lookahead can sometimes make the line number be off by one. Instead of saying something like “Error occurred at line #xxx” you might want to say that the error occurred near line #xxx.
As far as the rest, it’s up to you. You are going to have to capture the not-quite valid syntax and call the appropriate warning or error handler. See the O’Reilly “flex & bison” book for details; it has an entire chapter on error messages. An entire chapter is a bit too much to reproduce at this Q&A site.