编译原理实训，介绍了四个编译原理的实训课程，语义分析，语法分析，词法分析，词法识别-Compiler theory training, introduced the principle of the training course of four compilation, semantic analysis, syntax analysis, lexical analysis, lexical recognition

给出PL/0文法规范，要求编写PL/0语言的词法分析程序。-Gives the PL/0 grammar specification, requiring written PL/0 language lexical analysis program.