I have this project where I need to write a code to simulate a DFA to accept url's. The DFA part I have figured out is completely fine, but I am having some problems with the code. The first problem is when I run the code it seems to not go past the cout<<"enter y/n part. The second might be part of it but i get a lot of
27 left operand of comma operator has no effect [-Wunused-value]
27 right operand of comma operator has no effect [-Wunused-value]
27 error: expected ';' before ')' token
31 error: expected primary-expression before 'goto'
31 error: expected ')' before 'goto'
at each of the for loops for some reason
#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; } 
