Convert a whole integer to an array of integers

Hello everyone,

In this tutorial, we will see how we can convert an integer into an array of integers. First, what does that mean? What we mean is that the program will accept an integer number such as "76342986" and will convert it into an array of integers

7

6

3

4

2

9

8

6

so you can deal with any digit individually.

Why is that even useful?

Converting a whole integer into an array of integers can be useful in many ways:

·         Stem-and-leaf calculation

·         To create the largest possible number from a given number

·         Working on place values

·         Finding significant figures

·         You can write an application to convert numbers to corresponding strings

·         You can check divisibility of a number

·         To be able to express a number in extended form

and there are plenty other applications (in particular, math applications) where you will need to deal with the digits  individually.

So, how do we do that?

Here are the steps we're going to follow:

1-      Accept the number as string

2-      Convert the string-number into an array of characters

3-      Declare an array of integers that have the same length as the array of characters

4-      Apply the equation:

Array_of_numbers[] = array_of_characters[] – '0';

Which will return the number and will be stored in the array of integers.

E.g.,

If the first number in the array of characters is 7, then

Array_of_numbers[0] = array_of_characters[0] – '0';

// Array_of_numbers[0] = '7' – '0';

// Array_of_numbers[0] = 7;

                       And so on.

A question may pop up: how it works? Actually when we subtract characters here, we basically subtract ASCII values. So the ASCII value of 5 is 53 and for 0 is 48, so 53 – 48 = 5, and this similar to the numbers from 0 to 9.

what if the user entered a negative number?

If the user entered a negative number say -12332, then this will be the array_of_characters[]

-

1

2

3

3

2

So how do we handle such situation?

•        After converting the whole number to an array_of_characters[], we check the first location whether it has a negation sign or not
•     If it has the negation sign, then re-initialize the size of the Array_of_numbers to be array_of_characters.Length -1. And this is because the additional one space that the negation sign takes
•     We start converting the array_of_characters[] to Array_of_numbers[] from the second location of array_of_characters[]
•     To here, the Array_of_numbers[] will be:

1

2

3

3

2

   

•          Lastly, make the first number in the array negative:

          Array_of_numbers[0] = - Array_of_numbers[0];

To make sure that the code is correct, we add a sum variable to sum all the numbers and check the result whether it is correct or not.

Note: If you have a better way to solve the problem or to optimize the code, please feel free to comment it down. I will be happy to see your contribution.

Here is the full Csharp code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.ObjectModel;

namespace TestConsole
{

    class Program
    {
        static void Main(string[] args)
        {

            Console.WriteLine("Enter a number");
            string stringNumber = Console.ReadLine();
            char[] charnumbers = stringNumber.ToCharArray();
            int[] theNumbers = new int[charnumbers.Length];
           
            bool negativeNumber = false;
            int sum = 0;

            if (charnumbers[0] == '-')
            {
                negativeNumber = true;
                theNumbers = new int[charnumbers.Length - 1];
            }

            for (int i = 0; i < theNumbers.Length; i++)
            {
                if (negativeNumber == true)
                    theNumbers[i] = charnumbers[i + 1] - '0';
                else
                    theNumbers[i] = charnumbers[i] - '0';
            }

            if (negativeNumber == true)
                theNumbers[0] = -theNumbers[0];

            Console.WriteLine("the number is {0} digits", theNumbers.Length);
            for (int i = 0; i < theNumbers.Length; i++)
            {
                Console.WriteLine("[{0}] => {1}", i, theNumbers[i]);
                sum += theNumbers[i];
            }
            Console.WriteLine("The sum is {0}", sum);
            Console.ReadLine();
        }
    }
}