12.30 Recursive descent analysis

1#include <stdio.h>2#include <string.h>3 Charstr[Ten];4 intindex=0;5 voidE ();//e->tx;6 voidX ();//x->+tx|-tx| e7 voidT ();//T->fy8 voidY ();//y->*fy |/fy| e9 voidF ();//f-> (E) | IDTen intID ();//ID One intMain () A { -     intLen; -     intm; the  -printf"Please enter an arithmetic expression:"); -scanf"%s", str); -len=strlen (str); +str[len]='#'; -str[len+1]=' /'; + E (); Aprintf"Correct Statement! \ n"); atstrcpy (str,""); -index=0; -      -     return 0; - } - voidE () in { - T (); to X (); + } - voidX () the { *     if(str[index]=='+') $     {Panax Notoginsengindex++; - T (); the X (); +     }  A     Else if(str[index]=='-') the     { +index++; - T (); $ X (); $     }  - } - voidT () the { - F ();Wuyi Y (); the } - voidY () Wu { -     if(str[index]=='*') About     { $index++; - F (); - Y (); -     } A     Else if(str[index]=='/') +     { theindex++; - F (); $ Y (); the     } the } the voidF () the { -     if(ID ()) in     { theindex++; the     } About     Else if(str[index]=='(') the     {      theindex++; the E (); +         if(str[index]==')') -         { theindex++; Bayi}Else{ theprintf"\ nthe parse failed!\n"); theExit (0); -         } -     }  the     Else{ theprintf"Analysis Failure!\n");  theExit0); the     } -  } the intID () the { the      if(str[index]>='0'&&str[index]<='9')94     { the          while(str[index+1]>='0'&&str[index+1]<='9' ) the         { theindex++;98         } About         if(str[index+1]>='a'&&str[index+1]<='Z' ) -             return 0;101 102         return 1;103     }104      Else if(str[index]>='a'&&str[index]<='Z' ) the      {106          return 1;107      }108      Else 109          return 0; the      111}

12.30 Recursive descent analysis