Thread: Arrays

I have this assignment where i should be able to write in as many whole numbers as i want too and then end it with a negative number.
After the negative number the code should be able to print all the numbers backwards except for the negative one.

So something like this:

Whole N1: 302 "Then hit enter"
Whole N2: 32 --||--
Whole N3: 534 --||--
Whole N4: -302 --||--

The amount of positive whole numbers are: 3.
Your numbers backwards is: 203, 23, 435.



I don't really know of where to begin. The course is new and i am new to java. I can use whatever i like here so arrays would be
the best thing i guess but i don't know of where to start.

Any tips?

Okay so i can make a forloop that takes the numbers that i use and print them out.
But i can't find a way to store them in the array.. or atleast it doesn't look like i am "storing" them right.

	public static void main(String[] args) {
 
		Scanner input = new Scanner(System.in);
		int NUM[] = new int[100000];
		int nums = 0;
		int helhet = 0;
		int line = 0;
		//int lenght = input.nextInt();
 
		System.out.println("Type in a whole number!");
 
		for (int i = 1; i > 0; i++) {
			line++;
			helhet = input.nextInt();
			System.out.println("Line " + line + ": " + helhet + "");
			NUM[helhet] = helhet;
		}
 
		/// for (int k = lenght - 1; k >= 0; k--) {
		// System.out.print("K Value: " + k);
 
//		}
 
		// if (helhet < 0) {
		// System.out.print(":" + NUM);
		// }
	}
}

Okay but how do i store the values that i get from the loop into the array and then print them out later?

So.. i guess that this could work. However i feel like the value of "Data" changes and i cannot print all the numbers afterwards. In either case without the if statement then the program print out numbers so you write 38 and you get 38 etc.

But i still don't get the arrays. Any tips?


PS: Made a new code real quick because i am not on my main pc. Could've just copied but yeah..

	public static void main(String[] args) {
 
		int flee = 0;
		int Data[];
		Data = new int[1000000];
		Scanner in = new Scanner(System.in);
		int input = 0;
		System.out.println("Skriv in x antal värden och sedan ett negativt tal för att påvisa att det är klart!");
 
		for (int i = 1; i > 0; i++) {
			input = in.nextInt();
			flee++;
			System.out.println("Ditt värde är : " + "Antal värde:" + flee + "; " + input);
			Data[1000000] = input;
 
		}
		if (input < 0) { //Problem area! 
			System.out.print(Data);
			System.exit(input);
		}
 
	}
 
}

I am guessing that i am making things worse than they have to be..
But i am learning at the same time.

Feels like i could almost get this working... almost.

public static void main(String[] args) {
 
		Scanner input = new Scanner(System.in);
		int NUM[] = new int[500];
		int line = 0;
		int cause = 0;
 
		System.out.println("Type in a whole number!");
 
		for (int i = 0; i < 500; i++) {
			line++;
			NUM[i] = input.nextInt();
			System.out.println("Line " + line + ": " + ++cause + "");
			if (NUM[i] < 0) {
				for (int k = 0; k < NUM[k]; k++) {
					System.out.println("Here is the numbers: " + ++cause + NUM[k]);
				}
			}
		}
 
 
	}
}

Thanks Jim!

I almost got it working now!
But i had seen the assignment wrong. So what the program has to do is to print out all of the whole numbers that are positive and take the
numbers stored and print them out but backwards.

It does everything right except for when it prints because i cannot get it to print backwards. So if i input 1 and 2 then i can print back 1 and 2 but not in reverse order
such as 2 and 1.

public static void main(String[] args) {
 
		Scanner in = new Scanner(System.in);
 
		int num[] = new int[10000];
		int hell = 0;
 
		System.out.println("Write a couple of whole numbers and end with a negative one : ");
 
		for (int i = 0; i < 10000; i++) {
			num[i] = in.nextInt();
			System.out.println("Value " + (i + 1) + ": " + num[i]);
			hell++;
 
			if (num[i] < 0) {
				break;
			}
 
		}
 
		String Five = "Your values are: "; //Maybe there is something that could be changed here! Not sure...
		for (int i = 0; i < hell; i++) {
			Five += num[i];
			if (i < hell) {
				Five += ", ";
			}
		}
		System.out.println(Five);
		System.out.println("Amount of positive values : " + (hell - 1));
 
	}
 
}

Originally Posted by jim829

Hint: for loops can go from 0 to n with a positive increment or from n to 0 with a negative increment. You just need to adjust the parameters(e.g. starting point) to handle your list.

Regards,
Jim

Thank you Jim! Got it working now.