通过设计、编制、调试一个算术表达式的语法及语义分析程序，加深对语法及语义分析原理的理解，并实现词法分析程序对单词序列的词法检查和分析-Through the design, preparation, testing an arithmetic expression syntax and semantic analysis procedures, better understanding of the syntax and semantic analysis understanding of the principles and procedures for the realization of lexical analysis of the lexical word sequence and analysis of inspection