语法制导翻译

1、for循环语句翻译递归下降法输出三地址码/#define MAX 100#include#include#includechar strMAX;char ch;int turn;char strTokenMAX;int kind;int n=0;/存放strtoken元素的个数struct Word/结构体存放单词(int sort;char wordMAX;/ 存放 strtoken的内容;/recordx=new Word;Word *record12;/放所有识别出来的单词，分别存放他们的编号以及字符串，x是其下标/ 词法分析 /int buffer()/载入(int0;cout输入程序

2、，以“#”作为结束标志。endl;for(int n=0;n=MAX;n+)(for(;istri不可用，用C语言读入字符。if(stri=#)break;/如果尾数为识别码#,则表示程序读完，跳出循环.break;return(i); bool IsLetter(char ch)/ 判断是否是字母(if(ch=65&ch=97&ch=48&ch=57)return(true);elsereturn(false);char GetChar(int i)/ 读取字符(char ch;ch=stri;return(ch);char GetBC(char ch)/判断是不是空格或者换行，如果是，直接

3、读取下一个字符直道不再空白为止(if(ch=32|ch=10)(turn+;ch=GetChar(turn);ch=GetBC(ch);/ 递归实现return(ch);elsereturn(ch);void Concat()/连接，即为 strtoken赋值(strTokenn=ch;n+;int Reserve()/以单词为单位查找保留字，是则返回编码，不是则返回0,用来区分标志符和保留字 (if(strcmp(strToken, DIM0)=0)/调用 strcmp 函数实现，return(1);else if(strcmp(strToken,for0)=0)return(2);else

4、 if(strcmp(strToken,step0)=0)return(3);else if(strcmp(strToken,until0)=0)return(4);else if(strcmp(strToken,do0)=0)return(5);elsereturn(6);void clear()(n=0;/* 语法递归分析 */int A(int * c,int & q)(if(cq+=3)(if(cq=7)( q+;return 1;else (coutstep 右部出错endl;return 0;else (couterror stependl;return 0;int B(int *

5、 b,int & o)(if(bo+=4)(if(bo=7)( o+;return 1;else (coutuntil 右部出错endl;return 0;else (couterror untilendl;return 0;int S2(int * d,int & h)(if(dh+=6)(if(dh+=8)(if(dh=6|dh=7) h+; return 1;else cout赋值语句右部出错endl;return 0;else cout赋值语句缺少赋值运算符”endl;return 0;else cout赋值语句左部出错endl;return 0;int S1(int * m,int

6、& n)if(S2(m,n)if(A(m,n)if(B(m,n) return 1;else return 0;else return 0;else return 0;int S(int *a,int & z)if (az+=2)if (S1(a,z)if(az+=5)if(S2(a,z)(coutsucceed!endl;return 1;else return 0;else (couterror doendl; return 0;else return 0;else (couterror forendl; return 0;void main()(cout* 产生式 *endl;/ for

7、 step until do i j =coutfor S1 do S2endl; / 编号 2 3 4 5 6 7 8coutS2ABendl;couti=jendl;coutstepjendl;coutuntiljendl;int num;turn=0;num=buffer()-1;int x=0;/计识别的单词的个数for(;turn=num;turn+)/总循环,ch存放刚读入的字符，strtoken存放巳识别的标志付或保留字，turn是数 组str的下标(ch=GetChar(turn);ch=GetBC(ch);if(IsLetter(ch)(while(IsLetter(ch)&

8、turn=num|IsDigit(ch)&turnsort=kind;/12345 或 6/coutkind; 测试cout(;for(int i=0;iwordi=strTokeni;coutwordi;/输出识别的标志符或保留字cout”,kind”)”wordi=0;clear();x+;else if(IsDigit(ch)(while(IsDigit(ch)&turnsort=kind;/cout(;for(int i=0;iwordi=strTokeni;coutwordi;cout”,kind”)”wordi=0;clear();x+;else if(ch=)(kind=8;/r

9、ecordx=new Word;recordx-word0=;recordx+-sort=kind;cout”(=,kind”)”endl;elsecouterror input!endl;/* 语法分析 */int y;/*for(y=0;yx;y+)(coutsort ;/打印单词的编号。coutendl;*/int anaMAX;/存放词法分析得到的单词序列的编号的序列 int m;for(m=0;msort;/将 sort 作为数组保存起来/语法分析/int j=0;/ 制导翻译 /if(!S(ana,j) cout语法出错!”endl;else cout三地址码如下：endl;cou

10、twordi != 0)coutwordi+:coutword0;i=0;while (record 3-wordi != 0)coutwordi+;coutendl:cout101 goto 103”endl;coutwordi != 0)coutwordi+;cout：=”;i=0;while (record l-wordi != 0)coutwordi+;cout+”;i=0;while (record 5-wordi != 0)coutwordi+;coutendl:coutwordi != 0)coutwordi+;cout；i=0;while (record 7-wordi != 0)coutwordi+;cout go