Question

I need to set a global variable from a function and am not quite sure how to do it.

# Set variables
$global:var1
$global:var2
$global:var3

function foo ($a, $b, $c)
{
    # Add $a and $b and set the requested global variable to equal to it
    $c = $a + $b
}

Call the function:

foo 1 2 $global:var3

End result:

$global:var3 is set to 3

Or if I called the function like this:

foo 1 2 $global:var2

End result:

$global:var2 is set to 3

I hope this example makes sense. The third variable passed to the function is the name of the variable it is to set.

Answer 1

You can use the Set-Variable cmdlet. Passing $global:var3 sends the value of $var3, which is not what you want. You want to send the name.

$global:var1 = $null

function foo ($a, $b, $varName)
{
   Set-Variable -Name $varName -Value ($a + $b) -Scope Global
}

foo 1 2 var1

This is not very good programming practice, though. Below would be much more straightforward, and less likely to introduce bugs later:

$global:var1 = $null

function ComputeNewValue ($a, $b)
{
   $a + $b
}

$global:var1 = ComputeNewValue 1 2