编译原理实验_递归下降语法分析.doc

递归下降语法分析姓名：郝梦朔 学号：71107416 日期：2010-1-17一、 实验目的构造文法的语法分析程序，要求采用递归下降语法分析方法对输入的字符串进行语法分析，实现对词法分析程序所提供的单词序列的语法检查和结构分析，进一步掌握递归下降的语法分析方法。二、 实验内容编写为一上下文无关文法构造其递归下降语法分析程序，并对任给的一个输入串进行语法分析检查。程序要求能对输入串进行递归下降语法分析，能判别程序是否符合已知的语法规则，如果不符合（编译出错），则输出错误信息。三、 实验要求利用C语言编制递归下降分析程序，并对语言进行语法分析。（1） 待分析的语言的语法。用扩充额BNF表示如下。:=functionendfunc:=;:=:=ID=:=+|-:=*|/:=ID|NUM|()（2） 实验要求说明输入单词串以“#”结束，如果是文法正确的句子，则输出成功信息，打印“success”，否则输出“error”，具体例子如下。输入functiona=9;x=2*3;b=a+x;endfunc#输出success又如，输入：x=a+b*cendfunc#输出error（3）语法分析程序的算法思想为翟玉庆老师上课所讲。四、 实验源程序#include#includechar prog80,token8;char ch;int syn,p,m=0,n,sum,kk=0;char *rwtab6=function,if,then,while,do,endfunc;void scaner();void lrparser();void yucu();void statement();void expression();void term();void factor();void main()p = 0;printf(please input the string:n);doch = getchar();progp+ = ch;while(ch != #);p = 0;ch = progp+;scaner();lrparser();return;void scaner()for(n=0;n8;n+)tokenn=NULL;/printf(n%c in scaner(),ch);while(ch = | ch = n )ch = progp+;/printf(n%c in scaner(),ch);m = 0;if(ch=a) |(ch=A)while(ch=a) |(ch=A)|(ch=0)tokenm+ = ch;ch = progp+;syn=10;for(n=0;n6;n+)if(strcmp(token,rwtabn) = 0)syn = n+1;/printf(n%d in keyword,syn);break;tokenm+ = 0;else if(ch=0)sum=0;while(ch=0)sum = sum*10 + ch - 0;ch = progp+;syn = 11;elseswitch(ch)case :m = 0;tokenm+ = ch;ch = prog+p;if(ch = =)syn = 24;tokenm+ = ch;elsesyn = 23;ch = prog-p;break;case =:m = 0;tokenm+ = ch;ch = prog+p;if(ch = =)syn = 25;tokenm+ = ch;elsesyn = 18;ch = prog-p;break;case !:m = 0;tokenm+ = ch;ch = prog+p;if(ch = =)syn = 22;tokenm+ = ch;elsesyn = -1;break;case +:syn = 13;token0 = ch;break;case -:syn = 14;token0 = ch;break;case *:syn = 15;token0 = ch;break;case /:syn = 16;token0 = ch;break;case ;:syn = 26;token0 = ch;break;case (:syn = 27;token0 = ch;break;case ):syn = 28;token0 = ch;break;case #:syn = 0;token0 = ch;break;default:syn = -1;ch = progp+;void lrparser()if(syn =1)/printf(n%d,syn);scaner();/printf(n%d,syn);yucu();/*/printf(n%d after yucu(),syn);if(syn = 6)scaner();/printf(n%d in lrparser() after scaner(),syn);if(syn = 0 & kk = 0)printf(nsuccess!n);elseif(kk != 1)printf(error!need endfunc);kk = 1;elseprintf(error!need function);kk =1;return;void yucu()/printf(n%d in yucu() first,syn);statement();/printf(n%d after statement() in yucu(),syn);while(syn = 26)scaner();/syn = 6;/printf(n%d after scaner() in yucu(),syn);statement();return;void statement()/printf(n%d in statement() at first,syn);if(syn = 10)scaner();/printf(n%d after scaner() in statement(),syn);if(syn = 18)scaner();/printf(n%d after scaner when syn=18,syn);expression();/printf(n%d after expression(),syn);elseprintf(error! evaluate tag error);kk = 1;else if(syn = 6)return;else printf(error! the statement error!);kk = 1;return;void expression()/printf(n%d in expression at first,syn);term();while(syn = 13 | syn = 14)scaner();term();return;void term()/printf(n%d in term() at first,syn);factor();while(syn = 15 | syn = 16)scaner();factor();return;void factor()/printf(n%d in factor() at first,syn);if(syn = 10 | syn = 11)scaner();elseif(syn = 27)scaner();expression();if(syn = 28)scaner();elseprintf(er