我为行数和字符数编写了一个 lex 程序(.l 文件)
程序:

%{
  int charcount=0,linecount=0;
%}
%%
.charcount++
\n linecount++,charcount++;
%%
main()
{
yylex();
printf(“lines  %d”,linecount);
printf(“characters %d”,charcount);
}
int yywrap()
{
return 1;
}

 J:\> gcc lex.yy.c
 lccc.l:  In function 'main':
 lccc.l:13: error:  stray'\223' in program
 lccc.l:13: error:  'lines' undeclared (first use in this function )
 lccc.l:13: error:  (Each undeclared identifier is reported only once
 lccc.l:13: error:  for each function it appears in. )
 lccc.l:13: error:  stray'\224' in program
 lccc.l:13: error:  'd' undeclared (first use in this function )
 lccc.l:14: error:  stray'\223' in program
 lccc.l:14: error:  'characters' undeclared (first use in this function )
 lccc.l:14: error:  stray'\224' in program

最佳答案

您需要将自定义代码括在大括号中。并且后面没有分号:charcount++而且你不能用逗号分隔语句，所以linecount++, charcount++;应该是 linecount++; charcount++; .

试试这个:

%{
  int charcount=0, linecount=0;
%}
%%
.  {charcount++;}
\n {linecount++; charcount++;}
%%
main()
{
  yylex();
  printf("lines  %d", linecount);
  printf("characters %d", charcount);
}
// ...

关于compiler-construction - lex 使用来自 lex.yy.c 文件的 flex -gettin 输出，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8029855/