一个教学应用的编译器，pl0编译器基本实现了一个词法分析器的主要功能，但是有一些缺陷，这些缺陷是作者故意做的，以此可以让学生完善这些功能，从而达到让学生更好的了解编译器的目的-One of the application of the compilers, pl0 compiler lexer basically a main function, but there are some weaknesses which the author deliberately done, this can allow students to perfect these capabilities, so as to achieve better students understand the purpose of the compiler