Powershell command to check if the data type of variable is integer, if it has characters it should respond with a message "Enter Only number"

[int]$name = Read-Host Enter the KB number
If ($name -is [int]) { 
    wusa /uninstall /kb:$name
    write-Host "This will uninstall windows update KB$name"
} else {
    write-Host "Enter only the number"
}

Here in this PowerShell scripts, whenever a characters is typed is returns an error instead of message "Enter only the number".

PS C:\Users\User\Desktop> .\Test.ps1
45454
Enter the KB number: asfs
Cannot convert value "asfs" to type "System.Int32". Error: "Input string was not in a correct format."
At C:\Users\User\Desktop\Test.ps1:5 char:1
+ [int]$name = Read-Host Enter the KB number
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvalidCastFromStringToInteger

This will uninstall windows update KB0

Solution

The error you are facing is cause by this:

[int]$name = Read-Host Enter the KB number
^^^^^

By defining the int variable type, any non-int input will cause an error. For example:

PS C:\Users\Neko> [int]$test = read-host
ABC
Cannot convert value "ABC" to type "System.Int32". Error: "Input string was not in a correct format."
At line:1 char:1
+ [int]$test = read-host
+ ~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : MetadataError: (:) [], ArgumentTransformationMetadataException
    + FullyQualifiedErrorId : RuntimeException

Powershell tries to convert the string input to the type System.Int32 but since it is not possible as the input is a string, this error is caused which also causes the variable to not be defined whatsoever. If you are going to define it as a int, do it after the variable was initially defined like so:

:loop while ($name = read-host Enter the KB number)
    {
    $name -as [int] | findstr $name
    if ($?)
        {[int]$name = $name; break loop}
    else
        {Write-Output "Invalid Input"}
    } 
wusa /uninstall /kb:$name
write-Host "This will uninstall windows update KB$name"
}

or alternatively you can do:

:loop while ($name = read-host Enter the KB number){
    $ErrorActionPreference = 'SilentlyContinue'
    [int]$name = $name
    if (!($name -is [int]))
    {echo "Invalid input"} 
    else 
    {break loop}
    }
wusa /uninstall /kb:$name
write-Host "This will uninstall windows update KB$name"