Thread: GuessingGame problem

Hello, just wondering if anyone can help me with this problem. I had write a program which creates 100 random integers, each in the range 1 to 1000, inclusive. The user guesses a number and is told whether or not it is among the random numbers & this continues until the user guess correctly or enters 0 to signal that he/she gives up. The program had to include a static function called member which returns a boolean value indicating whether or not an integer x occurs in an integer array w where x and w are parameters.

Here is my code:

class GuessGame 
{
	static boolean member(int x, int[] w)//returns true if x occurs in array w
	{
		int i=0;
		while(i<w.length && i!=x)
			i++;
		if(i<w.length) //if found
			return true;
		else
			return false;
	}
	public static void main(String[] args) 
	{
		int[] nums = new int[1000];
		for(int i=0; i<nums.length; i++)// fill array with random numbers in the range 1..1000
		{
			nums[i] = (int)(1+(Math.random()*1000));
		}
		System.out.println("Take a guess..");
		int guess = Console.readInt();
		while(guess!=0)
		{
			if(member(guess, nums))
			{
				System.out.println("This number is among the random numbers.");
				break;
			}
			System.out.println("This number is not among the random numbers, try again.");
			guess = Console.readInt();
		}
	}//end main
}//end class

When i run this, it keeps saying the number is among the random numbers, even if it's not. Can anyone help me with this? Thank you

Sorry yes i understand what you mean. I was looking at another example I had done and thats what was embedded in the if statement. What could i use to determine if x is found? Would it be correct to use: if(w[i]==x) return true; ??

Originally Posted by newbie

Yeah, that would be what you're after.
Also consider replacing the while loop with a for loop, it's more convenient than storing a counter variable yourself.
Of course it will function exactly the same as your while, but it's ultimately down to your preference I suppose.

Regarding your program specification, int[] nums = new int[1000];
is a waste of memory, as you only need to store 100 not 1000 Integers.

(int)(1+(Math.random()*1000));
Deals with doubles, and you're obviously casting it into an int.

I'd personally recommend using nextInt(int n) method from the Random class for generating random numbers, but again, its up to you .
Have a go implementing what you suggested, and come back if you get stuck again.

Random (Java 2 Platform SE v1.4.2)

Thanks very much for the help I appreciate it Regarding the loops, the only reason i use a while loop is because my lecturer showed us that way & said its the simplest way Personally, I don't really see much of a difference in simplicity. The program is now running ok, but if i enter a number that isn't found in the array, it throws this exception:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 100
at GuessGame.member(GuessGame.java:10)
at GuessGame.main(GuessGame.java:26)

any ideas how to fix this?

Sorry I dont fully understand. i++ is the only thing present in the loop body, i'm not sure where you mean to put it

static boolean member(int x, int[] w)
	{
		int i=0;
		while(i<w.length && w[i]!=x)
		{
			i++;
		}
		if(w[i]==x)
			return true;
		else
			return false;
	}

All was needed was to change while(i<w.length.....) to while(i<w.length-1....) . Works perfectly now. Thanks for your help once again