通过设计编制调试一个具体的词法分析程序，加深对词法分析原理的理解，并掌握在对程序设计语言源程序进行扫描过程中将其分解为各类单词的词法分析方法。编制一个读单词过程，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显示）。-Debugging through the design of the preparation of a specific lexical analysis program, to deepen understanding of the principles of lexical analysis and control of the programming language in the scanning process will be the source for all types of word lexical decomposition analysis. The process of the preparation of a word read from the input source program, identify the meaning of each word independent, that is basically reserved words, identifiers, constants, operators, delimiters five categories, and in turn the output of each word in the internal code and the word sign their own values ​ ​ (when errors can be displayed " Error" , then skip the error part of the continued display).