Self-describing numbers: Difference between revisions

=={{header|PowerShell}}==

According to the Wiki definition, the sum of the products of the index and the

digit contained at the index should equal the number of digits in the number:

<lang PowerShell>

function Test-SelfDescribing ([int]$Number)

{

[int[]]$digits = $Number.ToString().ToCharArray() | ForEach-Object {[Char]::GetNumericValue($_)}

[int]$sum = 0

for ($i = 0; $i -lt $digits.Count; $i++)

{

$sum += $i * $digits[$i]

}

$sum -eq $digits.Count

}

</lang>

<lang PowerShell>

Test-SelfDescribing -Number 2020

</lang>

{{Out}}

<pre>

True

</pre>

It takes a very long while to test 100,000,000 numbers, and since they are already known just test a few:

<lang PowerShell>

11,2020,21200,321100 | ForEach-Object {

[PSCustomObject]@{

Number = $_

IsSelfDescribing = Test-SelfDescribing -Number $_

}

} | Format-Table -AutoSize

</lang>

{{Out}}

<pre>

Number IsSelfDescribing

------ ----------------

11 False

2020 True

21200 True

321100 False

</pre>