词法分析，词法分析阶段是编译过程的第一个阶段，是编译的基础。这个阶段的任务是从左到右一个字符一个字符地读入源程序，即对构成源程序的字符流进行扫描然后根据构词规则识别单词(也称单词符号或符号)。词法分析程序实现这个任务。词法分析程序可以使用Lex等工具自动生成-Lexical analysis, lexical analysis phase is to compile the first stage of the process is to compile the foundation. This phase of the task is a character from left to right to read a character into the source code, that constitute the source of the character stream is scanned and then identified under the rules of word formation word (also known as word symbol or symbols). Lexical analysis program to achieve this task. Lexical analysis program can use tools such as automatic generation of Lex