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Thread: Do while loop problem

  1. #1
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    Default Do while loop problem

    Hi all,
    My program is pretty simple, it involves a guessing game where the user is prompted to enter an amount of money to start with. After that the user guesses a number from 1 to 100 and depending on the number guessed, the game lets you know if it's too high or low. With that said, I am trying to insert a loop to prompt an error if the user enters an amount that's over $300 and allow the user to re-enter an amount. If the amount initially or after the error is <= to 300, then the user may proceed with the game. This is the code before the do/while loop is implemented:

    import java.io.IOException;
    import java.util.Random;
    import java.util.Scanner;
     
    public class guessinggame2 {
           public static void main(String[] args) throws IOException {
                   Scanner reader = new Scanner(System.in);
                   Random random = new Random();
     
                   int randomNumber,
                   dollars = 0,
                   balance = dollars,
                   guessedNumber = 0;
                   char runAgain = 'y';
     
                   randomNumber = random.nextInt(101);
                   		System.out.print("Welcome to the Guessing Game!" + "\n" );
                           System.out.print("The rules are simple, you have to guess the correct number and   " + "\n");
                           System.out.print("if it is wrong, you lose $10 and will be prompted on how close   " + "\n");
                           System.out.print("to the number you are. If you guess the number right, you win " + "\n");
                           System.out.print("$100 and can choose whether or not to continue playing or not." + "\n");
                           System.out.print("" + "\n");
                           System.out.print("How many dollars do you wish to start off with? (Maximum of $300) " + "\n");
                           dollars =reader.nextInt();
                   while (runAgain == 'y' || runAgain == 'Y')
                   {                      
                           System.out.print("Please pick a number between 1 and 100: ");
                           guessedNumber = reader.nextInt();
                           while (guessedNumber != randomNumber)
                           {  
                            if (guessedNumber < randomNumber)
                            {
                                                   dollars -= 10;
                                                   System.out.println("Too low!\nGuess again!\nYour balance is: $" + dollars + "\n");
                            }
     
                                           if (guessedNumber > randomNumber)
                                           {
                                                   dollars -= 10;
                                                   System.out.println("Too high\nGuess again!\nYour balance is: $" + dollars + "\n");
                                           }        
     
                                   System.out.print("Please pick a number between 1 and 100: ");
                                   guessedNumber = reader.nextInt();      
                           }
                           dollars += 50;
                           System.out.println("Congratulations, you got it!" +"\n");
                           System.out.println("Your balance is: $" + dollars + "\n");
                           System.out.print("Play again (y/n)? ");
                           runAgain = (char)System.in.read();
     
                           if (runAgain == 'n' || runAgain == 'N')
     
                           {
                                   System.exit(0);
                           }
                            if (runAgain == 'y' || runAgain == 'Y')
                        		   randomNumber = random.nextInt(101);
                   }
           }
    }

    And this is the code with the attempted do/while loop, which doesn't work:

    import java.io.IOException;
    import java.util.Random;
    import java.util.Scanner;
     
    public class guessinggame2 {
           public static void main(String[] args) throws IOException {
                   Scanner reader = new Scanner(System.in);
                   Random random = new Random();
     
                   int randomNumber,
                   dollars = 0,
     
                   guessedNumber = 0;
                   char runAgain = 'y';
     
                   randomNumber = random.nextInt(101);
                   		System.out.print("Welcome to the Guessing Game!" + "\n" );
                           System.out.print("The rules are simple, you have to guess the correct number and   " + "\n");
                           System.out.print("if it is wrong, you lose $10 and will be prompted on how close   " + "\n");
                           System.out.print("to the number you are. If you guess the number right, you win " + "\n");
                           System.out.print("$100 and can choose whether or not to continue playing or not." + "\n");
                           System.out.print("" + "\n");
                           System.out.print("How many dollars do you wish to start off with? (Maximum of $300) " + "\n");
                           dollars =reader.nextInt();
     
                           do{
     
                        	   System.out.println("Error, please enter a valid amount: ");
                        	   dollars =reader.nextInt();
                        	   while (dollars >= 301);
     
     
                   while (runAgain == 'y' || runAgain == 'Y')
                   {                      
                           System.out.print("Please pick a number between 1 and 100: ");
                           guessedNumber = reader.nextInt();
                           while (guessedNumber != randomNumber)
                           {  
                            if (guessedNumber < randomNumber)
                            {
                                                   dollars -= 10;
                                                   System.out.println("Too low!\nGuess again!\nYour balance is: $" + dollars + "\n");
                            }
     
                                           if (guessedNumber > randomNumber)
                                           {
                                                   dollars -= 10;
                                                   System.out.println("Too high\nGuess again!\nYour balance is: $" + dollars + "\n");
                                           }        
     
                                   System.out.print("Please pick a number between 1 and 100: ");
                                   guessedNumber = reader.nextInt();      
                           }
                           dollars += 50;
                           System.out.println("Congratulations, you got it!" +"\n");
                           System.out.println("Your balance is: $" + dollars + "\n");
                           System.out.print("Play again (y/n)? ");
                           runAgain = (char)System.in.read();
     
                           if (runAgain == 'n' || runAgain == 'N')
     
                           {
                                   System.exit(0);
                           }
                            if (runAgain == 'y' || runAgain == 'Y')
                        		   randomNumber = random.nextInt(101);
                   }
           }
    }
    }

    Any help/suggestions are greatly appreciated.
    Thank you.


  2. #2
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    Default Re: Do while loop problem

    Your problem is here:
      do {
    System.out.println("Error, please enter a valid amount: ");
    dollars =reader.nextInt();
    while (dollars >= 301);
    Is a syntax error.

    application context
    Last edited by daniel.j2ee; December 13th, 2011 at 05:02 PM.

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