PowerShell ConvertTo-PhoneNumber

August 17, 2012

The switch statement is the most powerful statement in the PowerShell language. This statement combines pattern matching, branching, and iteration all into a single control structure. – Bruce Payette “Windows PowerShell in Action”

Regex Switch

I’m using pattern matching, branching, and iteration. Plus I’m using the Regex switch.

function ConvertTo-PhoneNumber {            
            
    param(            
        [Parameter(Mandatory=$true)]            
        $query             
    )            
                
    $r = switch -Regex ( $query.ToCharArray() ) {            
        'a|b|c'   { 2 }            
        'd|e|f'   { 3 }            
        'g|h|i'   { 4 }            
        'j|k|l'   { 5 }            
        'm|n|o'   { 6 }            
        'p|q|r|s' { 7 }            
        't|u|v'   { 8 }            
        'w|x|y|z' { 9 }            
    }            
                
    "$r"            
}

Try It

ConvertTo-PhoneNumber TMobile

8 6 6 2 4 5 3

{ 6 comments… read them below or add one }

Steve G 08.18.12 at 8:29 pm: Doug, that’s one of your coolest PS functions so far, there’s so much going on in what appears to be a very simple expression.

I assume “$r” is equivalent to –> $r.toString()?

keep them coming!
-Steve
Doug Finke 08.18.12 at 9:35 pm: Thanks Steve.

$r is of type Object[]. Putting it in quotes, PowerShell does string concatenation.

Doug
Chris Warwick 08.20.12 at 4:14 am: Doug, how about this (the last replace is optional…):

function ConvertTo-PhoneNumber2 {

param(
[Parameter(Mandatory=$true)]
$query
)

$query -replace ‘[abc]‘, ’2′ `
-replace ‘[def]‘, ’3′ `
-replace ‘[ghi]‘, ’4′ `
-replace ‘[jkl]‘, ’5′ `
-replace ‘[mno]‘, ’6′ `
-replace ‘[pqrs]‘, ’7′ `
-replace ‘[tuv]‘, ’8′ `
-replace ‘[wxyz]‘, ’9′ `
-replace ‘[^0-9a-z]‘
}
Doug Finke 08.21.12 at 3:20 pm: Thanks for the post Chris. That works!

It’d be interesting to benchmark which approach is faster.

I like your use of brackets, []. I will update my sample to use that.

I wonder which regex is faster too, ‘a|b|c’ vs. ‘[abc]‘.

Doug
alzdba 09.27.12 at 7:02 am: I also added one line so it also accepts numbers !
function ConvertTo-PhoneNumber2 {
param([Parameter(Mandatory=$true)]
$query
)
$query -replace ‘[abc]‘, ’2′ `
-replace ‘[def]‘, ’3′ `
-replace ‘[ghi]‘, ’4′ `
-replace ‘[jkl]‘, ’5′ `
-replace ‘[mno]‘, ’6′ `
-replace ‘[pqrs]‘, ’7′ `
-replace ‘[tuv]‘, ’8′ `
-replace ‘[wxyz]‘, ’9′ `
-replace ‘[0-9]‘, “$_” `
-replace ‘[^0-9a-z]‘
}

#Benchmark
$( 0..500 | Measure-Command { ConvertTo-PhoneNumber 555dontcall } ).ticks
#9793984

$( 0..500 | Measure-Command { ConvertTo-PhoneNumber2 555dontcall } ).ticks
#1084970

Great solution.
Thank you both
alzdba 09.28.12 at 1:01 am: oh heck.
The addition I made ( -replace ‘[0-9]‘, “$_” ` ) proved to be totally useless and causes invalid results !
I’ve noticed that after my previous reply.
However after removing my line, the benchmark data is still valid, so the number of ticks still stand.
I’m sorry for the mishap. :blush: