if else 循环语句的程序设计

#include<iostream.h> #include<stdio.h> #include<string.h> #include<iomanip.h> #define MAX 100 static char INPUT[MAX]; /*存放输入的语句*/ static char str[MAX]; /*存放构成单词符号的字符串*/ static int mark[MAX]; static int i=0; static int j=0; static int m; static int n; /*struct Wd//结构体 存放单词 { char word[MAX];//存放str[]的内容 }; Wd *record[MAX];//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 */ char record[MAX][MAX]; int word() { if((INPUT[i]>=65&&INPUT[i]<=90)||(INPUT[i]>=97&&INPUT[i]<=122))/* 识别标识符和关键字*/ { str[j]=INPUT[i]; i++; j++; while((INPUT[i]>=65&&INPUT[i]<=90)||(INPUT[i]>=97&&INPUT[i]<=122 )||(INPUT[i]>=48&&INPUT[i]<=57)) { str[j]=INPUT[i]; i++; j++; } if(INPUT[i]!=' ')i--;/*使i回调*/ if(strcmp(str,"if")==0||strcmp(str,"IF")==0)return(1); else if(strcmp(str,"then")==0||strcmp(str,"THEN")==0)return(2); else if(strcmp(str,"else")==0||strcmp(str,"ELSE")==0)return(3); else return(0); } else if(INPUT[i]>=48&&INPUT[i]<=57)/*识别常数*/ { str[j]=INPUT[i]; i++; j++; while((INPUT[i]>=48&&INPUT[i]<=57)&&i<MAX) { str[j]=INPUT[i]; i++; j++; } if(INPUT[i]!=' ')i--; return(4); } else if(INPUT[i]=='<') { str[j]=INPUT[i]; i++; j++; if(INPUT[i]=='=') { str[j]=INPUT[i]; return(5); } else{ i--; return(6); } } else if(INPUT[i]=='>') { str[j]=INPUT[i]; i++; j++; if(INPUT[i]=='=') { str[j]=INPUT[i]; return(7); } else { i--; return(8); } } else if(INPUT[i]=='!') { str[j]=INPUT[i]; i++; j++; if(INPUT[i]=='=') { str[j]=INPUT[i]; return(9); } else { i--; return(-1); } } else if(INPUT[i]=='=') { str[j]=INPUT[i]; i++; j++; if(INPUT[i]=='=') { str[j]=INPUT[i]; return(10); } else { i--; return(11); } } else if(INPUT[i]=='+') { str[j]=INPUT[i]; return(12); } else if(INPUT[i]=='-') { str[j]=INPUT[i]; return(13); } else if(INPUT[i]=='*') { str[j]=INPUT[i]; return(14); } else if(INPUT[i]=='/') { str[j]=INPUT[i]; return(15); } else if(INPUT[i]==' ')return(16); else return (-1); } int _mark() { int len=0; while(len<strlen(INPUT)) { mark[n]=word(); if(mark[n]==16)//空格跳过、连接 { i++; len=i; n--; } else if(mark[n]!=-1)//错误标记、跳过 { i++; len=i; strcpy(record[n],str); cout<<n<<')'<<setw(10)<<str<<setw(10)<<mark[n]<<";"<<endl; } else { cout<<endl; cout<<"error！词法分析器分析到第"<<n+1<<"个单词符号这里发现错误！"<<endl; return (-1); break; } n++; for(m=0;m<MAX;m++) str[m]='\0'; j=0; } cout<<"单词的总数："<<n<<endl; } int S(int *a,int &z); int E(int *s,int &x); int A(int *d,int &c); int B(int *f,int &v); int C(int *q,int &w); int D(int *g,int &b); int S(int *a,int &z) { if(a[z++]==1){ if(E(a,z)){ if(a[z++]==2){ if(B(a,z)){ if(a[z++]==3){ if(B(a,z)){cout<<"文法分析成功"<<endl;return 1;} else return 0; } else {cout<<"出错在else"<<endl;return 0;} } else return 0; } else {cout<<"出错在then"<<endl;return 0;} } else return 0; } else {cout<<"出错在if"<<endl;return 0;} } int E(int *s,int &x) { if(D(s,x)){ //不合理s[x++]==0&&(s[x]==5||s[x]==6||s[x]==6||s[x]==8||s[x]==9||s[x]==10) if(A(s,x)){ if(D(s,x)){ cout<<"E成功"<<endl; return 1; } else {cout<<"E失败在id2"<<endl;return 0;} } else return 0; } else if(s[--x]==0){x++;cout<<"E成功"<<endl;return 1;} else {cout<<"E失败"<<endl;return 0;} } int A(int *d,int &c) { if(d[c]==5){c++;cout<<"A成功"<<endl;} else if(d[c]==6){c++;cout<<"A成功"<<endl;return 1;} else if(d[c]==7){c++;cout<<"A成功"<<endl;return 1;} else if(d[c]==8){c++;cout<<"A成功"<<endl;return 1;} else if(d[c]==9){c++;cout<<"A成功"<<endl;return 1;} else if(d[c]==10){c++;cout<<"A成功"<<endl;return 1;} else {cout<<"A失败"<<endl;return 0;} } int B(int *f,int &v) { if(f[v++]==0){ if(f[v++]==11){ if(f[v]==4){v++;cout<<"B成功"<<endl;return 1;} else if(D(f,v)){ if(C(f,v)){ if(D(f,v)){cout<<"B成功"<<endl;return 1;} else {cout<<"B失败在D"<<endl;return 0;} } else {cout<<"B失败在C"<<endl;return 0;} } else {cout<<"B失败在D"<<endl;return 0;} } else {cout<<"B失败在="<<endl;return 0;} } else {cout<<"B失败在id1"<<endl;return 0;} } int D(int *g,int &b) { if(g[b]==0){b++;cout<<"D成功"<<endl;return 1;} else if(g[b]==4){b++;cout<<"D成功"<<endl;return 1;} else {cout<<"D失败"<<endl;return 0;} } int C(int *q,int &w) { if(q[w]==12){w++;cout<<"C成功"<<endl;return 1;} else if(q[w]==13){w++;cout<<"C成功"<<endl;return 1;} else if(q[w]==14){w++;cout<<"C成功"<<endl;return 1;} else if(q[w]==15){w++;cout<<"C成功"<<endl;return 1;} else {cout<<"C失败"<<endl;return 0;} } int main() { int value=0; int sd=1,bj; char xh; cout<<"*********if_else产生式*********"<<endl; cout<<"S→if E then B else B"<<endl; cout<<"E→D A D | id1"<<endl; cout<<"D→id1 | num"<<endl; cout<<"A→< | > | == | != | >= | <= "<<endl; cout<<"B→id1=num | id1=D C D"<<endl; cout<<"C→+ | - | * | / "<<endl; cout<<"非终结符(S|E|D|A|B|C)"<<endl; cout<<"终结符(if|then|else|id1|num|<|>|==|!=|<=|>=|+|-|*|/)"<<endl; cout<<"*******************************"<<endl; cout<<endl; for(int ii=0;ii<MAX;ii++) for(int jj=0;jj<MAX;jj++) record[ii][jj]='\0'; cout<<"请输入条件语句："<<endl; gets(INPUT); //输入一个句子 cout<<endl; cout<<"词法分析分析出的单词及其对应的编码如下："<<endl; _mark(); cout<<endl; cout<<"******************************"<<endl; cout<<"递归分析过程"<<endl; if(!S(mark,value)) cout<<"语法分析失败"<<endl; else { cout<<"语法分析成功"<<endl; //for(int ii=0;ii<n;ii++)cout<<record[ii]<<endl; cout<<endl; cout<<"***********************"<<endl; cout<<"输出三地址"<<endl; cout<<'('<<"100"<<')'<<setw(15); while(strcmp(record[sd],"then")){ cout<<record[sd];sd++; } cout<<setw(10)<<"goto"<<'('<<"102"<<')'<<endl; cout<<'('<<"101"<<')'<<setw(15); sd++; bj=sd; while(strcmp(record[sd],"else"))sd++; sd++; while(sd<n){ cout<<record[sd];sd++; } cout<<setw(10)<<"goto"<<'('<<"103"<<')'<<endl; cout<<'('<<"102"<<')'<<setw(15); sd++; while(strcmp(record[bj],"else")){ cout<<record[bj];bj++; } cout<<endl; cout<<'('<<"103"<<')'<<setw(10)<<"……"<<endl; } return 0; }