自己编的一个小程序，供大家参考，有不足之处请提意见。

pl0修改后的源程序和报告 （1） 修改后的PL/0语言文本。包含词法分析（正规式），语法分析（BNF）。 （2） 有关修改后的PL/0编译/解释器的说明。详细说明你的编译器是如何编译新的PL/0语言程序的。指出你的程序中最精彩的部分，以及你为什么这样做，你是如何控制和恢复语义错误的。 （3） 给出你所改动后的编译器源程序清单，并标记出你所修改的部分。比较你的编译器和原来的编译器之间的差别。 （4） 说明你的编译器中可能存在的错误。 （5） 总结经验与教训，如果重做一遍，你会有哪些新的改进？ -err

c语言写的basic词法分析器-c language writes basic morphology analyzer

flex，词法自动生成工具，他可以在极短时间内帮助产生编译器的词法c源程序-flex, automatically generated lexical tools in a very short time he can help the compiler generate c source of lexical

多功能语法分析器。 -Multi-functional grammar analyzer. Multi-functional grammar analyzer.

Full support for extended regular expressions (those with intersection and complement); Support for some kinds of cycles in grammar; DFA-based operation; Unicode support; C++ only, requires a modern compiler; Lexical analyzers can be configured to get symbols from any input class (built-in support for std::istream, std::wistream and FILE *); Designed to work with Whale, but can work standalone or interface to other parsers.-Full support for extended regular expressions (those with intersection and complement); Support for some kinds of cycles in grammar; DFA-based operation; Unicode support; C only, requires a modern compiler; Lexical analyzers can be configured to get symbols from any input class (built-in support for std::istream, std::wistream and FILE*); Designed to work with Whale, but can work standalone or interface to other parsers.

这是一个非常经典的二叉平衡树，希望大家能够喜欢-This is a very classic balance of the two forks tree and I hope we can like

c语言的词法分析器 该程序是一个用c语言编写的词法分析器 -C language morphology analyzer this procedure is the morphology analyzer which compiles with the c language

编译原理(词法分析)- Translation principle (lexical analysis)

一个基于算符优先分析程序，是我的课程设计程序，大家可以参考-A priority based on operator analysis program, is my curriculum design process, everyone can refer to

本人写的简单C词法分析器，能基本实现C词法分析。可以供要求不是很严格的毕业设计。-I wrote a simple C lexical analyzer that can realize the basic lexical analysis of C. Can not very strict requirements for the graduation project.