用C语言编写一个PL/0词法分析器（约定所有字符均为小写，不包含大写字符），为语法语义分析提供单词，使之能把输入的字符串形



式的源程序分割成一个个单词符号传递给语法语义分析，并把分析结果（基本字，运算



符，标识符，常数以及界符）-Using C language to write a PL/0 lexical analyzer (agreed all characters are lowercase, uppercase characters not included), with words for grammatical and semantic analysis, which can put the string input

Split the source program into an analysis of transfer of each word symbol to the syntax and semantics, and the analysis results (basic word, operation

Fu, identifiers, constants and bound)