这是一个词法分析程序，是由文件读入要分析的字符串，分析分为三种情况：开头是字母，数字和非字母或数字的，即运算符和分界符。-This is a lexical analysis procedure is read from the document to analyze the string and analysis are divided into three types : the beginning of letters, numbers and non-alphanumeric data,