Where does the "newline" (\n) come from? (pattern matching using "flex")

I have an experimental flex source file(lex.l):

%option noyywrap
%{
  int chars = 0;
  int words = 0;
  int lines = 0;
%}
delim     [ \t\n]
ws        {delim}+
letter    [A-Za-z]
digit     [0-9]
id        {letter}({letter}|{digit})*
number    {digit}+(.{digit}+)?(E[+-]?{digit}+)?


%%

{letter}+ { words+开发者_高级运维+; chars += strlen(yytext); printf("Word\n"); }
\n        { chars++; lines++; printf("Line\n"); }
.         { chars++; printf("SomethingElse\n"); }

%%

int main(argc, argv)
int argc;
char **argv;
{
  if(argc > 1)
  {
    if(!(yyin = fopen(argv[1], "r")))
    {
      perror(argv[1]);
      return (1);
    }
  }

yylex();

printf("lines: %8d\nwords: %8d\nchars: %8d\n", lines, words, chars);
}

I created an input file called "input.txt" with "red apple" written in it. Command line:

$ flex lex.l
$ cc lex.yy.c
$ ./a.out < input.txt
Word
SomethingElse
Word
Line
lines:        1
words:        2
chars:       10

Since there is no newline character in the input file, why the "\n" in lex.l is pattern matched? (The "lines" is supposed to be 0, and the "chars" is supposed to be 9)

(I am using OS X.)

Thanks for your time.

It is very possible that your text editor has automatically inserted a newline at the end of the file.