初学者野牛flex [英] Beginner bison flex

问题描述

如何打印发生错误的行号.我尝试在yyerror()函数中使用yylineno并在.l文件中写入%option yylineno，但是在编译后给了我一个错误"yylineno undeclared (first use in this function)"，如果我将yylineno初始化为1，就给了我这个错误:

How can I print the line number on which an error occurred. I tried using yylineno in the yyerror() function and writing %option yylineno in the .l file but after compiling it gives me an error "yylineno undeclared (first use in this function)" and if I initialize yylineno as 1 it gives me this error:

error: redefinition of yylineno
lex.yy.c:273: note: previous definition of yylineno was here

推荐答案

还有第二种方法要求flex提供全局变量yylineno:命令行开关-l.如果那对您不起作用，您可以像Levine等人一样管理自己的全局对象.建议.在与换行符匹配的任何规则中将其递增.

There is a second way to ask flex to provide the global variable yylineno: the command line switch -l. If that doesn't work for you, you can manage your own global, as Levine et al. suggests. Increment it in any rule that matches a newline.

%{
    int mylineno = 1;
%}
%%
* * * 
\n  { mylineno++; }

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