Menu Program Infinite Loop on Invalid Input

[a275]

I have modified a menu program, but if you enter an invalid input (with the exception of an invalid integer) it goes into an infinite loop.
I would like to know how to fix this.

  #include <iostream> 

using namespace std;

int main()
{
  int option; 
  do 
  {
     
     cout << "1) Display Most Played MMORPGs " << endl;
     cout << "2) Display Most Played FPS " << endl;
     cout << "3) Display Most Played Survival Games" << endl;
     cout << "4) Exit Program " << endl;
cout << "***Note: Hit Ctrl+C in case of an error*** " << "\n \n " << endl;
     //Prompting user to enter an option according to menu
     cout << "Please select an option : ";
     cin >> option;  

     if(option == 1) 
     {
       
        cout << "Answer 1" << endl;
        cout << "Answer 2" << endl;
        cout << "Answer 3" << endl;
        cout << "Answer 4" << endl;
  cout << "\n \n " << endl;
   }
     else if(option == 2)
     {
        cout << "Answer 1" << endl;
        cout << "Answer 2" << endl;
        cout << "Answer 3" << endl;
        cout << "Answer 4" << endl;
cout << "\n \n " << endl;
}
     else if(option == 3) 
     {
        cout << "Answer 1" << endl;
        cout << "Answer 2" << endl;
        cout << "Answer 3" << endl;
cout << "\n \n " << endl;
}
     else if(option == 4) 
     {
       cout << "Terminating Program" << endl;
     }
     else 
     {
       
       cout << "Invalid Option entered" << endl;
     }
  }
  while(option != 4);

[AbstractionAnon]

Line 18: If a non-numeric is entered, the cin's fail bit will be set. You need to test the fail bit and if set issue a cin.clear() and cin.ignore ().
http://www.cplusplus.com/reference/istream/istream/ignore/
http://www.cplusplus.com/reference/ios/basic_ios/clear/

  if (! cin >> option)
  {  // fail bit set
      cin.clear ();
      cin.ignore (256);
  }
  else
  {  // cin operator good
  }

[a275]

Sorry, I am new to programming. If I were to simply copy and paste that code into line 19 would it work or would I have to work it into the program in a more complicated way?
Edit: I tested that and it works, but instead of returning the user to the menu it simply displays their invalid input. Also any input afterwards (correct or not) does the same thing and displays their invalid input.

[AbstractionAnon]

Lines 20-52 were meant to be within the range of the else

[a275]

How do I do that?

[AbstractionAnon]

I already told you. Move lines 20-52 of your program to between lines 24 and 25 of the snippet I posted.

#include <iostream> 
using namespace std;

void do_option (int option)
{   if(option == 1) 
    {   cout << "Answer 1" << endl;
        cout << "Answer 2" << endl;
        cout << "Answer 3" << endl;
        cout << "Answer 4" << endl;
        cout << "\n \n " << endl;
    }
    else if(option == 2)
    {   cout << "Answer 1" << endl;
        cout << "Answer 2" << endl;
        cout << "Answer 3" << endl;
        cout << "Answer 4" << endl;
        cout << "\n \n " << endl;
    }
    else if(option == 3) 
    {   cout << "Answer 1" << endl;
        cout << "Answer 2" << endl;
        cout << "Answer 3" << endl;
        cout << "\n \n " << endl;
    }
    else if(option == 4) 
    {   cout << "Terminating Program" << endl;
        exit (0);
    }
    else 
    {   cout << "Invalid Option entered" << endl;
    }  
}
  
int main()
{   int option; 
    do 
    {   cout << "1) Display Most Played MMORPGs " << endl;
        cout << "2) Display Most Played FPS " << endl;
        cout << "3) Display Most Played Survival Games" << endl;
        cout << "4) Exit Program " << endl;
        cout << "***Note: Hit Ctrl+C in case of an error*** " << "\n \n " << endl;
        //Prompting user to enter an option according to menu
        cout << "Please select an option : ";
        cin >> option;
        if (! cin)
        {   cout << "Not a valid option" << endl;
            cin.clear ();
            cin.ignore (256);
        }
        else
        {   //  Numeric value entered
            do_option (option);
        }
    }
    while (option != 4);
    return 0;
}

[a275]

I already told you. Move lines 20-52 of your program to between lines 24 and 25 of the snippet I posted.

That is what i needed to know. Thanks!

[AbstractionAnon]

Sorry I wasn't clear about that.

[a275]

Hm, when I try to compile it I receive this error (using g++ if that is relevant):

menu.cpp: In function ‘void do_option(int)’:
menu.cpp:27:16: error: ‘exit’ was not declared in this scope
exit (0);

[AbstractionAnon]

#include <cstdlib> 

[a275]

Oh, of course. Thank you.
Edit: I am having the same issue as earlier. Instead of returning the user to the menu it displays their input.
Edit 2: I think I solved it. cin.ignore (256); I changed that 256 to 1 and it seems to work now. Going to play with it some more and make sure it works.