0 is not [int] in PowerShell?
I understand that (mathematically) 0 is Int. But still
if (0 -as [int]){"Int"}else{"Not"}
returns Not
at least for me in PS 2.0.
Is this a bug in v2, or am I not understanding things? I've been working on the problem by testing -as [int] -and -ne 0
, but it's a pretty frustrating feeling, so I hope I'm missing something and have a better answer.
FYI, I'm specifically dealing with the seed computer name that needs the original index or the last computer name that needs indexing. The seed looks like Lab 1 - and the start index can be 0 or can be 1 depending on the situation. I just tested so that the last character was [int]
, knowing that - there would be no int. But when the first computer was Lab 1-00 , because the starting index was 0, I also get not [int]
, and everything gets ugly, and the next computer is Lab 1-0000 . Again, the extra condition works, just wondering if I'm not wrong in my expectation that 0 is [int]
.
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The test IF
is performed by calling any expression aside from the parsers and then evaluating the result as [bool]
.
0 -as [int]
returns 0. When [int] evaluates to [bool] (true / false) 0 is $ false, so the test always fails.
From the description of the problem, it sounds like you can actually test a string instead of [int].
if ($var -as [int] -is [int]) {"Int"} else {"Not"}
Perform this test without throwing an exception.
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Yes, it 0
has a type [int]
. You can see this for yourself using the method GetType
:
PS > (0).GetType() IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True Int32 System.ValueType PS >
The problem is you are using the wrong operator. You are using -is
for type testing, not -as
:
PS > 0 -is [int] True PS > if (0 -is [int]) {"Int"} else {"Not"} Int PS >
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0 -as [int]
just means 0 is an int. The result of the expression is still 0
, which is implicitly converted to false
.
Instead, you want to use 0 -is [int]
which means is 0 an int
and will evaluate to true
.
Additional literature: get-help about_Type_Operators
EDIT:
The comments below provide an example of how you can evaluate if the last character can be converted to int without throwing an exception:
function CheckLastChar($string){ $var = 0 $string -match ".$" | Out-Null if ([System.Int32]::TryParse($matches[0], [ref]$var)) { "It an int!" } else { "It NOT an int!" } }
PS C:\> CheckLastChar("Lab 1-") It NOT an int! PS C:\> CheckLastChar("Lab 1-000") It an int!
Although, I must say, mjolinor -as [int] -is [int]
solution is much nicer.
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