Java while problem

DisasterIRL

I am working on a java assignment for my first year in computer science in ITB.

At the moment I am haivng no trouble at all as most of my work is quite simple but for some reason at the end of the code(highlighted) there is a while that won't exit

The code is as follows

/******************************************************************/
/* Java Program for weekend festival			          */
/* Written by:   Sean O'Mahony                                    */
/* Course: Computing                                              */
/* Language:  Java                                                */
/* Data started:14/10/2008                                 	  */
/* Last update:14/10/2008                               	  */
/* Program description:						  */
/******************************************************************/

class project
{
	public static void main(String[] args)
	{


		int number_ticket, ticket_type;
		double cost=0;
		char go_again;
		String name;


		do
		{
			System.out.println("***************************************************************");
			System.out.println("*                                                             *");
			System.out.println("*   1). Day Ticket  96.50 Euro Per Person                     *");
			System.out.println("*   2). Weekend ticket with camping 224.50 Euro Per person    *");
			System.out.println("*   3). Weekend ticket no camping 177.50 Euro per person      *");
			System.out.println("*                                                             *");
			System.out.println("***************************************************************");

			System.out.println("Please enter the type of ticket you would like");
			ticket_type=Keyboard.readInt();

			while(ticket_type<1||ticket_type>3)
			{
				System.out.println("Invalid number, please enter a number between 1 and 3");
				System.out.println("Plese try again");
				ticket_type=Keyboard.readInt();
			}
			switch(ticket_type)
			{
				case 1:cost=96.50;  break;
				case 2:cost=224.50; break;
				case 3:cost=177.50;
			}  //end of switch

			System.out.println("Please enter your surname");
			name=Keyboard.readString();
			System.out.println("Please enter the number of tickets you which to purchase");
			System.out.println("The max amount is 4");
			number_ticket=Keyboard.readInt();

			while(number_ticket<1||number_ticket>4)
			{
				System.out.println("Invalid number, maximum number of tickets is 4");
				System.out.println("Please try again");
			}  //end of while loop

			cost=cost*number_ticket;

			System.out.println("Festivle Ticket Type= " + ticket_type);
			System.out.println("Surname= " + name);
			System.out.println("No in Party= " + number_ticket);
			System.out.println("Total cost= " + cost);

			System.out.println("Would you like to go again?");
			go_again=Keyboard.readChar();
			go_again=Character.toUpperCase(go_again);

			while(go_again!='Y'||go_again!='N')
			{
				System.out.println("Invalid, please enter either Y or N");
				System.out.println("Would you like to go again?");
				go_again=Keyboard.readChar();
			}  // end of while

		}while(go_again=='Y');  //end of while

		System.out.println("Thank you and goodbye");

	}  //end of main

}  //end of class

Webmonkey

while(go_again!='Y'||go_again!='N')

That means if you press Y then, you get boolean 0 || 1 which = 1 so your loop will be true even if you do press Y. What you should do is

while(go_again!='Y' && go_again!='N')

Now you get 0 && 1 for a Y pressed which is false, (exit while) which is what you want and vice versa if its N.

Also note that you should do a toUpper inside the while loop too as you are over writing the previous one outside the loop.

while(go_again!='Y' && go_again!='N')
			{
				System.out.println("Invalid, please enter either Y or N");
				System.out.println("Would you like to go again?");
                                go_again = Character.toUpperCase(Keyboard.readChar());
			}  // end of while

DisasterIRL

Webmonkey wrote: »

while(go_again!='Y'||go_again!='N')

That means if you press Y then, you get boolean 0 || 1 which = 1 so your loop will be true even if you do press Y. What you should do is

while(go_again!='Y' && go_again!='N')

Now you get 0 && 1 for a Y pressed which is false, (exit while) which is what you want and vice versa if its N.

Also note that you should do a toUpper inside the while loop too as you are over writing the previous one outside the loop.

Thank you very much my fine Sir!

I don't know why but that never crossed my mind. Thanks again and amazing responce speed

Webmonkey

No Probs, fixed code there, little typo.

Idgeitman

the minute i saw something to do with tickets and being a small program, it reminded me of the one I made when I started out in college, and turns out you were also in ITB :P

Creadak

while(go_again=='Y');

Uhm... you said you'd fixed your code, but does that semi-colon there not create an infinite while loop?

Webmonkey

Creadak wrote: »

while(go_again=='Y');

Uhm... you said you'd fixed your code, but does that semi-colon there not create an infinite while loop?

Its a do while loop hince you need the semi colon there at end to end the statement. Common mistake to forget this.

DisasterIRL

Webmonkey wrote: »

Its a do while loop hince you need the semi colon there at end to end the statement. Common mistake to forget this.

Even I knew that:P:D