设计、编制并调试一个词法分析程序，加深对词法分析原理的理解。要求用文件实现能判别出关键字、标识符、数字符、操作符、分隔符。-The design, development and debugging a lexical analyzer, and deepen their understanding of the principles of lexical analysis. Required to achieve file can judge keywords, identifiers, th