Im new and need help!

[jrelvi23]

You guys are basically going to be my best friends this semester!! Already, I appreciate your responses!!

Im having trouble adding a couple numbers that the user inputs in a string. So for example, if the user inputs "12", what I want it to do, is manipulate it to so when it prints, it wil read 3, or 2 if I choose to multiply them. My question is, what method should I use to accomplish this? and remember I am newbie! so speaks slowly! :p

[r035198x]

First, be careful with your requirements. If I enter "351", is that three numbers, two numbers or one number?

[jrelvi23]

lol... I almost hit "report" on you thinking it was "reply."

Here's the exercise that I am trying to do:

import java.util.Scanner;

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

//Create a Scanner
Scanner input = new Scanner(System.in);


System.out.print("Enter the first 9 numbers of an ISBN: ");
int firstNumbers = input.nextInt();

//int calcFirstNumbers = (d1 * 10 + d2 * 9 + d3 * 8 + d4 * 7 + d5 * 6 + d6 * 5 + d7 * 4 + d8 * 3 + d9 * 2);
//System.out.println("Adding the first 9 numbers equals to: " + calcFirstNumbers);


System.out.print("Your 10-digit ISBN Number is: " + firstNumbers);

}
}

When the user inputs 9 numbers, I need each of those individuals numbers to represent d1,d2,d3,d4...

so if the user inputs: "394834005", each number represents d1 = 3; d2 =9, etc.
each number will then calculate into the formula that is set above. I know I need to set up a checksum and there's more to the formula... but just dissecting those numbers is what I am having trouble with.. ..I hope I didn't lose you!

[Dieter]

did you learn about arrays?

[jrelvi23]

No... I do not think so. However the teacher is slowly draining my will to live so I may be wrong but I don't think so. I am basically teaching myself here. I am guessing there are other ways to do this without using arrays, though?

BTW, you guys are really fast! :D

[r035198x]

If the string represents single digit numbers then use the toCharArray method in the String class to get the individual characters.

[oxano]

problem here:

System.out.print("Enter the first 9 numbers of an ISBN: ");
int firstNumbers = input.nextInt();

9 numbers is a way to big nummer to put in an integer.
an integer's range is : −32,768 to +32,767
anything bigger or smaller will result in an error (overflow or something?)

Maybe the sc.nextInt() is smart enough to detect this and will only read the first 4-5 digits of the full 9 digits and return that so if you type in '9876543210' the sc.nextIn() will give '9876' . and leave '543210' in the buffer..... maybe. I would have to test this to be sure.

Anyway, the point is that you can better use a String to read it in.
String string = sc.next()

The easiest way would be to indeed use arrays. The only possibility i currently see with not using arrays is using the substring method.

for(int i=0 ; i<9 ; i++){
   string.substring(i,i+1)
}

(hope i didn't make any indexoutofbounds errors here)

PS: put code between code tags: [CODE] [/ CODE] (without the space in [/ CODE])

[Singing Boyo]

problem here:


9 numbers is a way to big nummer to put in an integer.
an integer's range is : −32,768 to +32,767
anything bigger or smaller will result in an error (overflow or something?)

Maybe the sc.nextInt() is smart enough to detect this and will only read the first 4-5 digits of the full 9 digits and return that so if you type in '9876543210' the sc.nextIn() will give '9876' . and leave '543210' in the buffer..... maybe. I would have to test this to be sure.

since when is 9 numbers too long for an int? You're thinking of a short.

Quote from The Java Tutorials:

# short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As with byte, the same guidelines apply: you can use a short to save memory in large arrays, in situations where the memory savings actually matters.

# int: The int data type is a 32-bit signed two's complement integer. It has a minimum value of -2,147,483,648 and a maximum value of 2,147,483,647 (inclusive). For integral values, this data type is generally the default choice unless there is a reason (like the above) to choose something else. This data type will most likely be large enough for the numbers your program will use, but if you need a wider range of values, use long instead.

@OP: Ase was mentioned above, use String.toCharArray() to get the individual characters, then use Integer.parseInt(c +""); (The + "" make it a string, which is what the parameter needs to be) to get the value.

Hope this helps,
SingingBoyo

[jrelvi23]

Yessssss!!! I got it to work! thanks a lot everyone! great site! :)