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powershellsyntaxstring-interpolation

What does $($variableName) mean in expandable strings in PowerShell?

I've seen a number of example scripts online that use this. Most recently, I saw it in a script on automating TFS:

[string] $fields = "Title=$($taskTitle);Description=$($taskTitle);Assigned To=$($assignee);"
$fields += "Area Path=$($areaPath);Iteration Path=$($iterationPath);Discipline=$($taskDisciplineArray[$i]);Priority=$($i+1);"
$fields += "Estimate=$($taskEstimateArray[$i]);Remaining Work=$($taskRemainingArray[$i]);Completed Work=$($tasktaskCompletedArray[$i])"

From what I can tell, $($taskTitle) seems to be equivalent to $taskTitle. Am I missing something? Is there any reason to use the parentheses and extra dollar sign?

Solution

  • The syntax helps with evaluating the expression inside it. 

    $arr = @(1,2,3)

$msg1 = "$arr.length"
echo $msg1 # prints 1 2 3.length - .length was treated as part of the string

$msg2 = "$($arr.length)"
echo $msg2 # prints 3

    You can read more at http://ss64.com/ps/syntax-operators.html