編譯原理詞法分析_遞迴下降分析法

#include <iostream.h>       
#include <stdlib.h>
#include <fstream.h>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        

char sym='#';
int iWS=1;
char wordString[100];
int flag=1;

void advance(void); void fE(void);
void fE1(void);     void fT(void);
void fT1(void);  void fF(void);
void errorYF(void);

void errorYF(void)
{
 flag=0;
 cout<<"error !";
 cout<<endl<<iWS<<endl;
}
void advance(void)
{
 if(wordString[iWS]=='/0')
 {
  sym='#';
  return;
 }
 //if(wordstring[iWS]=='0')
 sym = wordString[iWS++] ;
// cout<<"sym = "<<sym<<endl;
 
}
void fE(void)
{ 
 fT();
 fE1();
 //cout<<"end of FE";cout<<endl;
}
void fE1(void)
{
 if(sym=='+')
 {
  advance();
  if(sym=='#')
  {
   return;
  }
  fT();
  fE1();
 }
}
void fT(void)
{
 fF();
 fT1();
}
void fT1(void)
{
 if(sym=='*')
 {
  advance();
  if(sym=='#')
  {
   return;
  }
  fF();
  fT1();
 } 
}
void fF(void)
{
 if(sym=='i')
 {
  advance();
  if(sym=='#')
  {
   return;
  }
 }
 else if(sym=='(')
 {
  advance();
  if(sym=='#')
  {
   return;
  }
  fE();
  if(sym==')')
  {
   advance();
   if(sym=='#')
   {
    return;
   }
  }
  else
  { 
   errorYF();
  }
 }
 else
 {
  errorYF();
 }
}

main()
{
 cin>>wordString;
 sym=wordString[0];
 fE();
 if(flag)
  cout<<wordString<<" is rigth!";
 cout<<endl;
 return(0); 
}