轉到問題和for循環問題

Question

我有這個項目，我需要編寫一個代碼來模擬DFA接受url的。我已經發現的DFA部分是完全正確的，但我在代碼中遇到了一些問題。 第一個問題是，當我運行的代碼似乎不走過去的COUT < <「輸入y/n的一部分。 第二個可能是它的一部分，但我得到了很多逗號

27左操作數操作者沒有影響[-Wunused值]

逗號操作的27右操作數沒有任何效果[-Wunused值]

27錯誤：預期「;」之前「）」令牌

31錯誤：預期主表達式之前「轉到」

31錯誤：「之前轉到」

在每個爲出於某種原因

迴路預期「）」

#include <iostream> 
#include <string.h> 
#include <stdlib.h> 
using namespace std; 
int main() { 
    char asdf='y'; 
    string str; 
    int stringlength,state; 
    while (asdf=='y'){ 
     start: 
     cout << "Do you want to enter a string?(y/n)\n"; 
     cin >> asdf; 
     cout << "Enter the string:\n"; 
     cin >> str; 
     stringlength=str.size(); 
     state=0; 
     //transition states q0 start 
      //w means goto q1,increment state by 1 
      if(str[0]=='w'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q1; 
      } 
      //. means trap state,loop the rest of the char's and output trap state and output "rejected", then return to start 
      if(str[0]=='.'){ 
       state=stringlength-state; 
       for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
      } 
      //not w and not . means goto q7 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q7; 

     q1: 
      //w means goto q2 
      if (str[1]=='w'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q2; 
      } 
      //. means go to q6 
      if (str[1]=='.'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q6; 
      } 
      //not w and not . means goto q7 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q7; 
     q2: 
      //w means goto q3 
      if (str[2]=='w'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q3; 
      } 
      //. means go to q6 
      if (str[2]=='.'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q6; 
      } 
      //not w and not . means goto q7 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q7; 
     q3: 
      //w means goto q3 
      if (str[3]=='.'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q4; 
      } 
      //not . means goto q7 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q7; 
     q4: 
      //. mean trap state 
      if (str[4]=='.'){ 
       state=stringlength-state; 
       for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
      } 
      //everything else goes to q5 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q5; 
     q5: 
      //. means goto q6 
      if (str[state]=='.'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q6; 
      } 
      //everything else goes back to q5 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q5; 
     q6: 
      //c means goto q8 
      if (str[state]=='c'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q8; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
       cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
      } 
      cout << "rejected\n"; 
      goto start; 
     q7: 
      //. means goto q6 
      if (str[state]=='.'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q6; 
      } 
      //everything else goes back to q7 
      cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
      state++; 
      goto q7; 
     q8: 
      //o means goto q9 
      if (str[state]=='o'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q9; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
     q9: 
      //m means goto q10 
      if (str[state]=='m'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q10; 
      } 
      //. means goto q11 
      if (str[state]=='.'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q11; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
     q10: 
      //compare length of string to state,if it matches there are no more char in string and is accepted 
      if (stringlength==state){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       cout << "accepted\n"; 
       goto start; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
     q11: 
      //j means goto q12 
      if (str[state]=='j'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q12; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
     q12: 
      //p means goto q13 
      if (str[state]=='p'){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       state++; 
       goto q13; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
     q13: 
      //compare length of string to state,if it matches there are no more char in string and is accepted 
      if (stringlength==state){ 
       cout << "character:"<<str[state]<<" "<<"state:"<<state<<"\n"; 
       cout << "accepted\n"; 
       goto start; 
      } 
      //everything else goes to trap state 
      state=stringlength-state; 
      for(state,state>0,state--){ 
        cout << "character:"<<str[stringlength-state]<<" "<<"state:trap\n"; 
       } 
       cout << "rejected\n"; 
       goto start; 
     } 
return 0; 
} 

Answer 1

你需要，而不是使用分號逗號的三個表達式中for迴路分開：

  for(state,state>0,state--){ 
        ^-------^ Change these to ;