more info on my question, ADDING LARGE INTEGERS, in java arrays

[johnathan]

I need help in writing the addition , subtraction etc. method.

eample the add method must add large intergers,
say 2500 + 69587562. each number is entered in the subscript individually.


this is what i have done so far.I created the class,constructors


public class Example
{
private int[] values;
private int min;
private int max;


Scanner Key= new Scanner(System.in);

public Example()
{
values=20;
min=0;
max=20;
}

public int ReadSize( int size)
{

System.out.println("Enter the size of the array.")
size=key.nextInt();

for(int min=0; min<size.length;min ++)
{
values[min]=key.nextInt();
}
}

[r035198x]

I need help in writing the addition , subtraction etc. method.

eample the add method must add large intergers,
say 2500 + 69587562. each number is entered in the subscript individually.


this is what i have done so far.I created the class,constructors


public class Example
{
private int[] values;
private int min;
private int max;


Scanner Key= new Scanner(System.in);

public Example()
{
values=20;
min=0;
max=20;
}

public int ReadSize( int size)
{

System.out.println("Enter the size of the array.")
size=key.nextInt();

for(int min=0; min<size.length;min ++)
{
values[min]=key.nextInt();
}
}

You will want to use code tags next time when posting code. Your constructor does not correctly initialize the array. If you want the array to store 20 integers you do

values = new int[20];

Now about that LARGE aspect. Either your array stores integers (type int), Integers (the Integer class) or long for larger integers or type Long. All these store integers deepending on the size of the integers required.
Look up their bounds and decide which one best suits your numbers

[r035198x]

If you need more help on this same problem, post in this same thread instead of starting a new thread for the same problem

[johnathan]

You will want to use code tags next time when posting code. Your constructor does not correctly initialize the array. If you want the array to store 20 integers you do

values = new int[20];

Now about that LARGE aspect. Either your array stores integers (type int), Integers (the Integer class) or long for larger integers or type Long. All these store integers deepending on the size of the integers required.
Look up their bounds and decide which one best suits your numbers

I NEED UR HELP IN Writing at least one method, thanks



here is the full question;

create a class called large integer that uses an int array to store very large integers and perform arithmetic and logic operations.
given default constructot 40element array to hold large integer and sets the current length of array to 0 and max to 40.

provide methods, to perform addition, subtraction, output a large integer,compares two integers for equality.

[r035198x]

I NEED UR HELP IN Writing at least one method, thanks



here is the full question;

create a class called large integer that uses an int array to store very large integers and perform arithmetic and logic operations.
given default constructot 40element array to hold large integer and sets the current length of array to 0 and max to 40.

provide methods, to perform addition, subtraction, output a large integer,compares two integers for equality.

import java.util.Scanner;
public class LargeInteger {
    private int[] number;
    private int max;
    public LargeInteger() {
        number = new int[40];
        max = 0;
    }
 
    //If you've done exception handling, you should use it here
    public LargeInteger(int max) {
        if(max > 40) {
            System.out.println("I can only store 40 digit numbers");
        }
        else {
            number = new int[40];
            this.max = max;
        }
    }
    //****Be careful when writting this one!
    //public int[] add(int[] num) {
 
    //}
    public void setDigit(int digit, int position) {
        number[position] = digit;
    }
    public String toString() {
        String num = "";
        for(int i = 0;i < max; i++) {
            num = num + number[i];
        }
        return num;
    }
 
    public static void main(String[] args) {
        Scanner key= new Scanner(System.in);
        System.out.print("Enter the number of digits in the number: ");
        int size = key.nextInt();
        LargeInteger large = new LargeInteger(size);
        for(int i = 0; i < size; i++) {
            large.setDigit(key.nextInt(), i);
        }
 
        System.out.println("Number stored is: "+large.toString());
 
    }
}

[johnathan]

THANKS r035198x,

will keep u posted as i progress with this problem.

[johnathan]

the addition method i need help with must do for example 125895+3567904.


the read statement looks some thing like this
[quote]for ( int i=array.length -1; i >=0; i - -)
array[i]=key.nextInt();
/QUOTE]

Note this is a 1dim array.

[r035198x]

[quote=johnathan]the addition method i need help with must do for example 125895+3567904.


the read statement looks some thing like this

for ( int i=array.length -1; i >=0; i - -)
array[i]=key.nextInt();
/QUOTE]

Note this is a 1dim array.

Are you having problems with reading in the numbers or adding the numbers?

[johnathan]

problem with adding of numbers

[r035198x]

problem with adding of numbers

The easiest way is to cheat it as follows:
declare an empty string s = "";
get each character in the array and append it to the string so that if the array had {4,6,7,8} as its values, the string s would now have "4678".
convert the string to a Long value and do the addition on Long values. Convert the Long value back to a string and read character by character into an int[] to get the number back to int[] format.

A more interesting "fair" approach would be to try to loop through the arrays from right to left, adding the corresponding values considering carrys. This is not too difficult actually as for each addition you check if the number exceeds 10. If not, fine just set that value. If it exceeds the unit value simply result - 10 and the carry is always 1

[johnathan]

could u wirte a method for me to see what it would look like, doing it the "FAIR method. thanks

[r035198x]

could u wirte a method for me to see what it would look like, doing it the "FAIR method. thanks

should look something like this. I have to go for now but you should make the neccessary changes to your code to make this compile and then try to fine tune it to get the correct results. I 'll be in tommorrow morning about 8 hrs from now but others may be able to help you before then

public LargeInteger add(LargeInteger num) {
        int size = num.getMax() > getMax() ? num.getMax(): getMax();
        LargeInteger result = new LargeInteger(size + 1);
 
        for(int i = 0; i < size; i++) {
            int resultPos = size;
            int carry = 0;
            int numPos = num.getMax();
            int thisPos = number.getMax();
            int unit = 0;
            int sum = carry + num.getDigit(numPos) + number.getDigit(thisPos);
            if(sum > 10) {
                unit = sum - 10;
                carry = 1;
            }
            else {
                carry = 0;
                unit = sum;
            }
            result.setDigit(unit, resultPos);
            resultPos = resultPos - 1;
            numPos = numPos - 1;
            thisPos = thisPos - 1;
        }
        return result;
 
 
 
    }

[johnathan]

this is what the program look like.

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

example test= new example (5);
example test2= new example(6);

example test3= new example(7);

test.readinfo();
test.printnum();

test2.readinfo();
test2.printnum();

test3.add(test,test2);



this is the class that i have so far. would u kindly help with the addition
subtraction methods. sorry am going to copy and paste this here.




public class example
{
private int [] values;


public example ()
{
values= new int[40];

}

public example(int size)
{
values=new int [size];
}

public void readinfo()
{
int ctr=0;
String asknum=JOptionPane.showInputDialog("Enter the numbers.");

for( int i=asknum.length() -1; i >=0; i--)
{
values [ctr]=asknum.charAt(i)-48;
ctr ++;
}
}

public void printnum()
{
for(int i=0; i<values.length; i ++)
{
JOptionPane.showMessageDialog(null,"Display the numbers." + values[i]);

}
}

public void add( )
{

[r035198x]

this is what the program look like.

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

example test= new example (5);
example test2= new example(6);

example test3= new example(7);

test.readinfo();
test.printnum();

test2.readinfo();
test2.printnum();

test3.add(test,test2);



this is the class that i have so far. would u kindly help with the addition
subtraction methods. sorry am going to copy and paste this here.




public class example
{
private int [] values;


public example ()
{
values= new int[40];

}

public example(int size)
{
values=new int [size];
}

public void readinfo()
{
int ctr=0;
String asknum=JOptionPane.showInputDialog("Enter the numbers.");

for( int i=asknum.length() -1; i >=0; i--)
{
values [ctr]=asknum.charAt(i)-48;
ctr ++;
}
}

public void printnum()
{
for(int i=0; i<values.length; i ++)
{
JOptionPane.showMessageDialog(null,"Display the numbers." + values[i]);

}
}

public void add( )
{

Are we still going the right direction here?

[johnathan]

am sorry, but i am.
that is what i came up with for the read statement, now following that i need help in the addition method, note please take a look at the program also.

[johnathan]

i need hepl with the addition and subtraction method.above you will see what i did so far.

also how do you declare a class within a class method. example.
the program would be:

example test=new example()
example test2=new example()
example test3=new example()

test.readinfo();
test2.readinfo()
test3(test,test2) HOW IS THIS REPRESENTED INT THE CLASS METHOD

public void add( WHAT GOES IN HERE)



THANKS FOR HELPING.

[johnathan]

Is This Correct.



public void add( examplexx a, examplexx b)
{
int carry=0;
int sum=0;

for(int i=0; i<values.length; i ++)
{
sum=carry + values.length + values.length;


if( sum >=10)
{
sum= sum-10;
carry =1;
}
else
{
carry =0;
}

}
JOptionPane.showMessageDialog(null, "The final sum is . " + sum);
}

[r035198x]

Is This Correct.



public void add( examplexx a, examplexx b)
{
int carry=0;
int sum=0;

for(int i=0; i<values.length; i ++)
{
sum=carry + values.length + values.length;


if( sum >=10)
{
sum= sum-10;
carry =1;
}
else
{
carry =0;
}

}
JOptionPane.showMessageDialog(null, "The final sum is . " + sum);
}

All I can say is this depends on where the method is. If the method is the number class (which in this case is examplexx?) then the method signature should be

public examplexx add(examplexx a)

. This is how I think you should be doing it as you could tell for my draft method for add that I did above(If you looked at it).

Now your method is taking in two objects a and b and doing absolutely nothing with them?

[r035198x]

Needless for me to point out that values is not defined in your method and so the method will not compile anyway.