Powershell函数中的参数传递

Question

I am facing a problem to add loop count with a variable and than pass it to function and print details. please suggest your wise suggestion.

My code is shown below:

function CheckErrorMessage {
    [CmdletBinding()]
    Param (
        [Parameter(Mandatory = $true, Position = 0)]
        [ValidateNotNullOrEmpty()]
        $Plugin

      , [Parameter(Mandatory = $true, Position = 1)]
        [ValidateNotNullOrEmpty()]
        $Report_Decission       
)

switch ($Plugin){

    'plugin-1' {

        $Report_Decission  

    }

    'plugin-2' {

       $Report_Decission  
    }

    Default {

   }
}
}#functions ends here

$test_1 = "no report"
$test_2 = "with report"

for($i=1; $i -ne 3; $i++){

CheckErrorMessage 'plugin-1' "$test_$i"  # i want to sent $test_1 or $test_2 from here
CheckErrorMessage 'plugin-2' "$test_$i"
}

when i run this, it prints

1
1
2
2

but i want the output like:

no report
no report
with report
with report

Thanks in advance.

Answer 1

You have to actually invoke that expression, so the variable expands, and you have to escape $ with `, so it doesnt try to expand it

CheckErrorMessage 'plugin-1' $(iex "`$test_$i")

Invoke-Expression:

The Invoke-Expression cmdlet evaluates or runs a specified string as a command and returns the results of the expression or command. Without Invoke-Expression, a string submitted at the command line would be returned (echoed) unchanged.

Reference: https://msdn.microsoft.com/en-us/powershell/reference/5.1/microsoft.powershell.utility/invoke-expression

edit: another way to do that (probably better and safer) by Mathias

$ExecutionContext.InvokeCommand.ExpandString("`$test_$i")

Answer 2

An alternative method that is a little more understandable is to use Get-Variable .

...
$test_1 = "no report"
$test_2 = "with report"

for($i=1; $i -ne 3; $i++) {
  CheckErrorMessage 'plugin-1' (Get-Variable "test_$i").Value
  CheckErrorMessage 'plugin-2' (Get-Variable "test_$i").Value
}