In Powershell what is the idiomatic way of converting a string to an int?

Question

The only method I have found is a direct cast:

> $numberAsString = \"10\"
> [int]$numberAsString
10

Is this the standard approach in

Answer 1

$source = "number35"

$number=$null

$result = foreach ($_ in $source.ToCharArray()){$digit="0123456789".IndexOf($\_,0);if($digit -ne -1){$number +=$\_}}[int32]$number

Just feed it digits and it wil convert to an Int32

Answer 2

Using .net

[int]$b = $null #used after as refence
$b
0
[int32]::TryParse($a , [ref]$b ) # test if is possible to cast and put parsed value in reference variable
True
$b
10
$b.gettype()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Int32                                    System.ValueType

note this (powershell coercing feature)

$a = "10"
$a + 1 #second value is evaluated as [string]
101 

11 + $a # second value is evaluated as [int]
21

Answer 3

For me $numberAsString -as [int] of @Shay Levy is the best practice, I also use [type]::Parse(...) or [type]::TryParse(...)

But, depending on what you need you can just put a string containing a number on the right of an arithmetic operator with a int on the left the result will be an Int32:

PS > $b = "10"
PS > $a = 0 + $b
PS > $a.gettype()

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Int32                                    System.ValueType

You can use Exception (try/parse) to behave in case of Problem

Answer 4

A quick true/false test of whether it will cast to [int]

[bool]($var -as [int] -is [int])

Answer 5

I'd probably do something like that :

[int]::Parse("35")

But I'm not really a Powershell guy. It uses the static Parse method from System.Int32. It should throw an exception if the string can't be parsed.

Answer 6

Building up on Shavy Levy answer:

[bool]($var -as [int])

Because $null is evaluated to false (in bool), this statement Will give you true or false depending if the casting succeeds or not.