通过设计、变形和调试词法分析器（又称扫描器），了解词法分析的组成 结果，不同种类单词的识别方法，掌握由单词的词法规则出发，然后再用程序实现词法分析器的设计方法。-By design, deformation and debugging the lexical analyzer (also known as scanner), to understand the composition of the results of lexical analysis, different types of word recognition method, master the rules starting from the lexical word, and then use the program to achieve lexical analyzer design.