Alter script variable value from inside PowerShell function

Question

I like C# so much better than PS but this time I'm forced to write a script... I need to alter "global" variable from inside a function without passing the variable as parameter. Is it even possible? Here is an abstract:

$a = 0
$b = 0
$c = 0
function Increment($var1, $var2)
{
$a = $var1
$b = $var2
$c++
}

Unlike C# in PS function variable are function scope bound and they remain unchanged outside of the scope of the function if used as described above. How can I make this work so the script variable are accessed by reference?

Possible duplicate of How to modify parent scope variable using Powershell. — rrirower
– rrirower, Commented Nov 6, 2014 at 16:47
In general this violates the purpose of a function (alter variables outside of its own scope). You can modify variables in a parent scope, but there are usually other ways to solve the problem. Keep in mind that PowerShell can return multiple values from a function. — Bill_Stewart
– Bill_Stewart, Commented Nov 6, 2014 at 17:27

Chris Mills · Accepted Answer · 2014-11-06 21:28:50Z

4

Try using the PowerShell global variable definition:

$global:a = 0
$global:b = 0
$global:c = 0
function Increment($var1, $var2)
{
    $global:a = $var1
    $global:b = $var2
    $global:c++
}

answered Nov 6, 2014 at 21:28

Chris Mills

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Bill_Stewart · Accepted Answer · 2014-11-06 17:35:30Z

3

If you really need to modify by reference, you can use [Ref], e.g.:

$a = 1
function inc([Ref] $v) {
  $v.Value++
}
inc ([Ref] $a)
$a  # outputs 2

answered Nov 6, 2014 at 17:35

Bill_Stewart

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