Parser - Segmentation fault when calling yytext

Question

My parser is recognizing the grammar and indicating the correct error line using yylineno. I want to print the symbol wich caused the error.

int yyerror(string s         


        

Answer 1

Depending on the version of lex you are using, yytext may be an array or may be a pointer. Since it is defined in a different compilation unit, if it is an array and you declare it as a pointer, you won't see any error messages from the compiler or linker (linker generally don't do type checking). Instead it will treat the first several characters in the array as a pointer and try to dereference it and probably crash.

If you are using flex, you can add a %pointer declaration to the first section of your .l file to ensure that it is a pointer and not an array