I am writing a script to copy files to multiple computers by taking source file, hostname list and destination location as the inputs. Following is the script (removed actual copy-item command for debugging);

function mycopyfile{
param($sourcefile, $hostlist, $filedestination)
Write-host $sourcefile
Write-host $hostlist
Write-host $filedestination
}
$sourcefile = $args[0]
$hostlist = $args[1]
$filedestination = $args[2]
mycopyfile($sourcefile, $hostlist, $filedestination)

When I run this I get the following output;

PS C:\powershell scripts> .\paratest.ps1 c:\abc.txt d:\cde.txt scripts
c:\abc.txt d:\cde.txt scripts

As you can see all the three variables are assigned to "$sourcefile" inside the function and therefore when used with the copy-item command it fails because $hostlist and $filedestination are null.

How can I pass the variables ( "c:\abc.txt", "d:\cde.txt" and "scripts") correctly?

PS : I have tried with single and double quotes but all failed. If I do write-host just before calling mycopyfile then the variables are showing correctly. Just running function with three values also display them properly so I think this relates to error is value passing.

Try this:

param (
    [String[]]$Computer,
    [String]$Path,
    [String]$Destination
)

function mycopyfile
{
    param (
        [String[]]$Computer,
        [String]$Path,
        [String]$Destination
    )
   
    Write-Host $Computer
    Write-Host $Path
    Write-Host $Destination
}

mycopyfile -Computer $Computer -Path $Path -Destination $Destination

I changed the variable names to make it more consistent with existing variable names in PowerShell.

The reason you got all your values assigned to $sourcefile is that is that your invocation of the mycopyfile function passed only one object to the function:

mycopyfile($sourcefile, $hostlist, $filedestination)

Is equivalent to:

mycopyfile -sourcefile @($sourcefile, $hostlist, $filedestination)

The correct way to invoke the function is:

mycopyfile -sourcefile $sourcefile -hostlist $hostlist -filedestination $filedestination

Or by using positional parameters:

mycopyfile $sourcefile $hostlist $filedestination

You really should consider changing the parameter names to be more consistent with powershell conventions.

I think it is unfortunate that powershell "functions" are declared as functions because they are very clearly not used like functions.