编写一个LEX输入文件，使之生成可计算文本文件的字符、单词和行数且能报告这些数字的程序。单词为不带标点或空格的字母和/数字的序列。标点和空白格不计算为单词。(Write a LEX input file to generate programs that can calculate characters, words and rows of text files, and can report these numbers. Words are sequences of letters and n