该程序要实现的是一个读单词过程，从输入的源程序中，识别出各个具有独立意义的单词，即基本保留字、标识符、常数、运算符、分隔符五大类。并依次输出各个单词的内部编码及单词符号自身值。（遇到错误时可显示“Error！”，然后跳过错误部分继续进行）-The program to achieve is a read word process, from the input source program, identify each independent meaning of words, namely, basic reserved words, identifiers, constant, operators, delimiter five categories. And the output of each word in turn the internal encoding symbols and the words itself value. (encounters an Error can be displayed "Error!", then skip the wrong part to continue)