编译原理词法分析器，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，其基本思想示根据扫描到单词符号的第一字符的种类，拼出相应的单词符号。-Lexical analyzer compiler theory, algorithms, the basic task is to identify the string representation of the source word with independent significance of symbols, the basic idea of ​ ​ the word shown to sign the scanning of the first characters of the species, spell out the appropriate word sign .