Powershell function Restart PC

Question

I want to create a function that take a array of pc and check if a pc name in parameter match with a pc name in the array at index of $i but when i create this function my function has a bug, the bug is $nomPeripherique is empty but i call it with "DESKTOP-QVRFEN4"

$tableauPeripherique= @("DESKTOP-QVRFEN4","DESKTOP-QVRETTD")

function Redemarrer($tableauPeripherique,$nomPeripherique){
    for ($i = 0; $i -lt $tableauPeripherique.Length; $i++)
    {
        if ($tableauPeripherique[$i] -eq $nomPeripherique)
        {
            Restart-Computer -ComputerName $nomPeripherique
        }
        else
        {
          
            echo "nom de peripherique n'est pas présent dans la liste"
        }
    }   
}

Redemarrer($tableauPeripherique,"DESKTOP-QVRFEN4")

Answer 1

Your are calling the function incorrectly. This is a common mistake for New PowerShell users as in many programming languages the function call has the arguments parenthetically stated after the Function name.

The call should look like:

Redemarrer $tableauPeripherique "DESKTOP-QVRFEN4"

No comma & no parens. The way you are calling it you're passing an entire array as the first argument. As such there's no second argument to compare to within the loop.

Personally I prefer advanced parameters. While there's a lot to know on the topic of Advanced Functions and their parameters there's still a low barrier to entry.

function Redemarrer
{
    Param(
        [Parameter(Mandatory = $true, Position = 0)]
        [String[]]$tableauPeripherique,
        
        [Parameter(Mandatory = $true, Position = 1)]
        [String]$nomPeripherique
    ) # End Param block...

    Process{
        for ($i = 0; $i -lt $tableauPeripherique.Length; $i++)
        {
            if ($tableauPeripherique[$i] -eq $nomPeripherique) {
                Restart-Computer -ComputerName $nomPeripherique                    
            }
            else {          
                Write-Output "nom de peripherique n'est pas présent dans la liste"
            }
        }
    } # End Process Block...
}

Note: You do not need Write-Output or it's alias echo . More importantly the function will return the string if & when the else block fires. This can be problematic if you are assigning the function return and/or piping to another command. In short if your only intent is to write something to the console use Write-Host instead. However, as you get more advanced there are reasons not to do that either.

Of course this answer is a poor substitute for the topic. One good relatively entry level book on the matter is "Learn PowerShell Scripting in a Month of Lunches" by Don Jones & Jeffrey Hicks. Incidentally Don Jones has a lot to say about Write-Host .