实现编译器的词法分析，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）-Achieve compiler lexical analysis, from the input source program to identify each word has an independent significance, that is the basic retention of the word, identifiers, constants, operators, delimiters five categories. And followed by all the output of the internal code word and the word itself the value of symbols. (Encountered an error when the display