设计、编制并调试一个词法分析程序。

算法的基本任务是从字符串表示的源程序中识别出具有独立意义的单词符号，其基本思想是根据扫描到的单词符号的第一个字符种类，拼出相应的单词符号，如果扫描到的单词符号是关键字，则到关键字种别码表中查出相应的种别码，并将其种别码和单词符号本身存入二元组-Design, preparation and commissioning of a lexical analyzer.

Basic task of the algorithm is to identify the string representation of the source word with independent significance of symbols, the basic idea is to scan a word according to the first character types of symbols, spell out the appropriate word sign, if the scan to the word Symbol is the keyword, the code table to the keyword kind kind was found in the corresponding code, and its kind into the code and the word symbol itself tuple