Programming Forums > Application Development > C++

Ade · Feb 9th, 2005, 4:16 AM

Hi guys, me again with another pissing college assignment......

Basically we need to make a programme that will simulate a telephone. It all works fine and is great and everthing is good in the world. Until, I'm doing error testing and find that when I input a coin value as a character such as 'h' it completly trips out and goes into an infinate loop!

Here's the code for the function.....

(Toggle Plain Text)

int coins () // the coin input is stored as a function as it is used twice
{
 
  for(;;)
  {
  cin>> value;
  
    if (value == 0)
    {
		break;
    }
    
    else
    {}

	if (value != 10 &&
	    value != 20 &&
	    value != 50 &&
	    value != 100)
	{
		value = 1;
	}
  
  switch(value)
  {
    case 10:
    total = total + value;
    remaining = total / charge;
    cout<< endl << "You entered " << value << "p. Your total is "
      << total << "p. That equals " << remaining << " seconds. "
        << endl << "Enter another coin or '0' to dial."
          << endl << endl;
	break;

	case 20:
    total = total + value;
    remaining = total / charge;
    cout<< endl << "You entered " << value << "p. Your total is "
      << total << "p. That equals " << remaining << " seconds. "
        << endl << "Enter another coin or '0' to dial."
          << endl << endl;
	break;
	
	case 50:
    total = total + value;
    remaining = total / charge;
    cout<< endl << "You entered " << value << "p. Your total is "
      << total << "p. That equals " << remaining << " seconds. "
        << endl << "Enter another coin or '0' to dial."
          << endl << endl;
	break;
	
	case 100:
    total = total + value;
    remaining = total / charge;
    cout<< endl << "You entered " << value << "p. Your total is "
      << total << "p. That equals " << remaining << " seconds. "
        << endl << "Enter another coin or '0' to dial."
          << endl << endl;
	break;

	default:
    cout<< endl << "Your last coin was not valid, please try again"
      << " using one of the accepted coins."
        << endl << endl;
	break;

  }

  cout.flush();

  }

  return 0;
}

My teacher suggested that cout.flush() would solve the problem, but needless to say it didn't.

basically I need to be able to make it so the only values that can be entered are 10, 20 ,50 and 100.

cheers guys
Ade

Eggbert · Feb 9th, 2005, 8:23 AM

Aside from using a nonstandard method to read keystrokes, the only good way to go about what you want is to validate the input:

(Toggle Plain Text)

#include <iostream>
#include <limits>

using namespace std;

// Clear stream state
template <typename Ch, typename Traits>
basic_ios<Ch, Traits>& clear ( basic_ios<Ch, Traits>& io )
{
  io.clear();
  return io;
}

bool valid_coin ( int coin )
{
  return coin == 10 || coin == 20 || coin == 50 || coin == 100;
}

int main()
{
  int coin;

  while ( true ) {
    cout<<"Enter 10, 20, 50, or 100: ";
    if ( !( cin>> coin >> clear ) || !valid_coin ( coin ) ) {
      cerr<<"Invalid entry, please try again"<<endl;
      // Empty the stream of bad characters
      cin.ignore ( cin.rdbuf()->in_avail() );
    }
    else
      break; // Everything is okay
  }

  cout<<"You entered: "<< coin <<endl;
  cin.get();
}

Ade · Feb 9th, 2005, 9:44 AM

Oh my god!!

Eggbert, you're not dead!!

PS thanks for the reply !

Ade · Feb 9th, 2005, 4:40 PM

OK, I just tested your code Egg and it does the same as mine, if I enter a character such as L, y, t etc. it enters an infinate loop.

I have no idea why????

Feb 9th, 2005, 4:16 AM	#1
Ade Hobbyist Programmer Join Date: Oct 2004 Location: England, UK Posts: 139 Rep Power: 0	restricting cin Hi guys, me again with another pissing college assignment...... Basically we need to make a programme that will simulate a telephone. It all works fine and is great and everthing is good in the world. Until, I'm doing error testing and find that when I input a coin value as a character such as 'h' it completly trips out and goes into an infinate loop! Here's the code for the function..... (Toggle Plain Text) int coins () // the coin input is stored as a function as it is used twice { for(;;) { cin>> value; if (value == 0) { break; } else {} if (value != 10 && value != 20 && value != 50 && value != 100) { value = 1; } switch(value) { case 10: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; case 20: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; case 50: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; case 100: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; default: cout<< endl << "Your last coin was not valid, please try again" << " using one of the accepted coins." << endl << endl; break; } cout.flush(); } return 0; } int coins () // the coin input is stored as a function as it is used twice { for(;;) { cin>> value; if (value == 0) { break; } else {} if (value != 10 && value != 20 && value != 50 && value != 100) { value = 1; } switch(value) { case 10: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; case 20: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; case 50: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; case 100: total = total + value; remaining = total / charge; cout<< endl << "You entered " << value << "p. Your total is " << total << "p. That equals " << remaining << " seconds. " << endl << "Enter another coin or '0' to dial." << endl << endl; break; default: cout<< endl << "Your last coin was not valid, please try again" << " using one of the accepted coins." << endl << endl; break; } cout.flush(); } return 0; } My teacher suggested that cout.flush() would solve the problem, but needless to say it didn't. basically I need to be able to make it so the only values that can be entered are 10, 20 ,50 and 100. cheers guys Ade __________________ Don't wound what you can't kill Last edited by Ade; Feb 9th, 2005 at 4:20 AM.

Feb 9th, 2005, 8:23 AM	#2
Eggbert Professional Programmer Join Date: Nov 2004 Posts: 250 Rep Power: 4	Aside from using a nonstandard method to read keystrokes, the only good way to go about what you want is to validate the input: (Toggle Plain Text) #include <iostream> #include <limits> using namespace std; // Clear stream state template <typename Ch, typename Traits> basic_ios<Ch, Traits>& clear ( basic_ios<Ch, Traits>& io ) { io.clear(); return io; } bool valid_coin ( int coin ) { return coin == 10 \|\| coin == 20 \|\| coin == 50 \|\| coin == 100; } int main() { int coin; while ( true ) { cout<<"Enter 10, 20, 50, or 100: "; if ( !( cin>> coin >> clear ) \|\| !valid_coin ( coin ) ) { cerr<<"Invalid entry, please try again"<<endl; // Empty the stream of bad characters cin.ignore ( cin.rdbuf()->in_avail() ); } else break; // Everything is okay } cout<<"You entered: "<< coin <<endl; cin.get(); } #include <iostream> #include <limits> using namespace std; // Clear stream state template <typename Ch, typename Traits> basic_ios<Ch, Traits>& clear ( basic_ios<Ch, Traits>& io ) { io.clear(); return io; } bool valid_coin ( int coin ) { return coin == 10 \|\| coin == 20 \|\| coin == 50 \|\| coin == 100; } int main() { int coin; while ( true ) { cout<<"Enter 10, 20, 50, or 100: "; if ( !( cin>> coin >> clear ) \|\| !valid_coin ( coin ) ) { cerr<<"Invalid entry, please try again"<<endl; // Empty the stream of bad characters cin.ignore ( cin.rdbuf()->in_avail() ); } else break; // Everything is okay } cout<<"You entered: "<< coin <<endl; cin.get(); }

Feb 9th, 2005, 9:44 AM	#3
Ade Hobbyist Programmer Join Date: Oct 2004 Location: England, UK Posts: 139 Rep Power: 0	Oh my god!! Eggbert, you're not dead!! PS thanks for the reply ! __________________ Don't wound what you can't kill

Feb 9th, 2005, 4:40 PM	#4
Ade Hobbyist Programmer Join Date: Oct 2004 Location: England, UK Posts: 139 Rep Power: 0	OK, I just tested your code Egg and it does the same as mine, if I enter a character such as L, y, t etc. it enters an infinate loop. I have no idea why???? __________________ Don't wound what you can't kill

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Programming Forums > Application Development > C++

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