此程序是对条件语句进行翻译，输入一个条件语句，例如：if B then C1 else C2，先进行词法分析，词法分析的主要任务是：从左到右逐个字符地对源程序进行扫描，产生一个个的单词符号，把作为字符串的源程序改造成为单词符号串的中间程序，词法分析是编译的基础，词法分析的功能是输入源程序，输出单词符号（关键字，标识符，常数，运算符，界符），词法分析完成之后，再进行LL（1）语法分析，语义分析，最后输出四元式（语法分析，属性文法，四元式的相关知识技术描述如下）-This procedure is a conditional statement to be translated and enter a conditional statement, for example: if B then C1 else C2, preceded by lexical analysis, lexical analysis of the main tasks are: characters one by one from left to right scan of the source code to create a In the words of the symbols, the source code as a string of symbols into strings of words among the procedures, lexical analysis is the basis of the compiler, lexical analysis of the function is to enter the source, the output word symbols (keywords, identifiers, constants, operator Fu, Fu-border), lexical analysis is complete, another LL (1) syntax analysis, semantic analysis, the final output quaternion type (syntax analysis, attribute grammar, style quaternion descr iption of knowledge and technology related to the following)