How can I convert a number into an array of digits?

Question

I'm trying to find a way to convert a number into an array of digits, similar to a character array, and still be able to perform mathematical operations on the array.

My first thought was to convert the number to a string, then to a character array, and then convert the array back to Int32 type. However, this has some unexpected results. For example, [int[]](1024).ToString().ToCharArray() results in the following array:

I do get what's happening here - PowerShell is treating the digits as ASCII characters, and converting them into their numeric values. However, that doesn't help me solve my problem.

What's the "right way" to convert numbers into single-digit integer arrays?

Keith Hill · Accepted Answer · 2013-11-14 02:08:44Z

4

Try this:

[char[]]'1024' | %{$_ - 48}

This will convert the characters to ints of the correct value:

C:\PS> [char[]]'1024' | %{$_ - 48} | %{$_.GetType().Name}
Int32
Int32
Int32
Int32

Here is a "mathy" version that works with an int:

C:\PS> $number = 1024
C:\PS> $numDigits = [math]::Floor([math]::Log10($number)) + 1
C:\PS> $res = @()
C:\PS> for ($i = 0; $i -lt $numDigits; $i++) {$res += $number % 10; $number = [Math]::Floor($number / 10)}
C:\PS> $res[($res.count-1)..0]
1
0
2
4

edited Nov 14, 2013 at 2:08

answered Nov 13, 2013 at 20:46

Keith Hill

204k44 gold badges370 silver badges377 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Iszi Over a year ago

Ah, so easy because the ASCII values are all 48 higher than the digit values. Not exactly "pure", but it works!

Keith Hill Over a year ago

The other option is to use [Math]::Log10() to determine number of digits and then continuously take modulo 10 and divide by 10.

mjolinor · Accepted Answer · 2013-11-13 21:30:37Z

3

OK.

[int[]][string[]][char[]]'1024'
([int[]][string[]][char[]]'1024').gettype()
1
0
2
4

IsPublic IsSerial Name                                     BaseType                   
-------- -------- ----                                     --------                   
True     True     Int32[]                                  System.Array

Starting with 1024, cast it to [char[]] to separate the digits. Then cast the chars to string to make the int conversion literal text, rather than ascii code.

Different tack, starting with [int], and minimizing casts:

$n = 1024
$array = [int[]](($n -split '') -ne '')

$array
$array.GetType()


1
0
2
4

IsPublic IsSerial Name                                     BaseType                   
-------- -------- ----                                     --------                   
True     True     Int32[]                                  System.Array

edited Nov 13, 2013 at 21:30

answered Nov 13, 2013 at 20:50

mjolinor

68.7k7 gold badges118 silver badges141 bronze badges

2 Comments

Iszi Over a year ago

This works if your number is already a string. Is there a way to do it if it's an integer, preferably without having to do another conversion into a string?

mjolinor Over a year ago

Posted another version

Collectives™ on Stack Overflow

How can I convert a number into an array of digits?

2 Answers 2

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related