A subtle difference between PowerShell ForEach and ForEach-Object

This blog post explains the major differences between PowerShell's ForEach statement and ForEach-Object cmdlet. There is a subtle difference, however, not mentioned in the post.

ForEach statement will not loop into a $null array variable, while ForEach-Object cmdlet will loop it once with a $null value. This may bite you with NullExceptions.

Here is a code snippet to demonstrate the issue.

	$myArray = $null
	# No loop
	ForEach($i in $myArray){
	'In ForEach'
	$i
	}
	# Loop once with $null value
	$myArray | ForEach-Object {
	'In ForEach-Object'
	$_
	}

view raw ForEachDiff.ps1 hosted with ❤ by GitHub