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Next, let's take a look at some new PowerShell 7 operators that were

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designed to make it easier to work with null values.

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These will make your head hurt a little bit, and they will

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take some time to get your head around.

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And I encourage you, again, to try the demos that I have in the course

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downloads so you can see how these things work for yourself.

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But at least let me give you a quick introduction to these operators.

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So I'm going to create a variable, $n, and basically

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assign a null value to it using $null,

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a special built‑in variable in PowerShell. The

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null‑coalescing operator is the two question marks.

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So if the left side of that operator is null,

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then evaluate or run the code that's on the right side.

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So if $n is null, then use the Write‑Warning command and say,

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hey, show me that the variable is null,

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which is exactly the result that I am expecting.

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Here's another example.

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So I'm going to assign the result of the expression

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$PSEdition ??, null‑coalescing,

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I'm not quite sure what a good way to describe the the two

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question marks is yet. If the left side is not null,

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then the right side is never used.

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So, $PSEdition should exist on all computers. And so if it does exist,

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PowerShell will assign that value to $v. Otherwise, if for some

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reason it doesn't exist, then unknown will be assigned to the value

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of $v. And because $PSEdition exists,

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then $v has a value, in this case, of Core because I'm

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running this on a PowerShell 7 system.

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So this null‑coalescing operator becomes a handy shortcut way

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comparing values to see if it's null or not and then deciding

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what else to do, very quick, simple,

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handy way. Related to that is the null‑coalescing assignment operator.

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That's the two question marks and the equal sign.

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So in this situation, we're going to assign the value from the right‑hand

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side to the left‑hand side if the left‑hand side is null.

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So $n is assigned the value of null. If $n is null,

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then we're going to give it a value of foo.

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So now, if I were to look at $n, I would see that it has a

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value of foo, and sure enough, it does.

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So let's rerun that command, $n, if it's null, then assign a value

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of bar. What do you think the value of $n is now, considering what I

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just did a moment ago? If you guessed foo, you are correct. Because

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$n was null to begin with,

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I assigned it a value of foo because $n was null, $n is no longer null,

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so the bar command never runs.

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So let's look at this from a more practical perspective. I'm going to create

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a variable, $p, and I want that value of p to be all the processes that have

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a working set size of greater than 1 gigabyte.

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If $p is null, if that Get‑Process command doesn't return anything,

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then $p will have null, in which case, I want to assign a value of 0.

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So because the Get‑Process command resulted in no processes, the

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null‑coalescing assignment command ran successfully, assigned a value of

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0 to $p, and you can see that $p has a value of 0.

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The last null‑related operator I want to talk about is the question mark period.

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And this is an operator that we use when we're trying to access members

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of an object, and specifically, methods of an object.

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So I'm going to, just to show you first how things normally work, and

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then we'll show how it would work when things are null.

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So I run Get‑Process for an existing process such as the current

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PowerShell process and save that to a variable $p, and now I want

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to invoke a method of an object.

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All objects have a ToString method, so this is a safe thing to test with.

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So if I do $p.ToString(),

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and remember when you invoke methods, you need to include the

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parentheses, I get the result that I expect.

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And this works because $p is not null.

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But, what if $p was null? Now in my demo here, I'm just

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going to assign a value of null to $p.

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But maybe in the real world, you forgot to create $p, or maybe

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you're using $p that was defined by some external process that

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failed to create it, and you have no idea.

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And this happens a lot in PowerShell. We work with things that maybe I got a

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result, maybe I didn't, let's see. And again, these are things that you'll

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probably work with more when you get to scripting,

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but we can work with this in the console as well.

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So I have $p. And in this particular case, it's

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null, but maybe I don't know that.

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Now if I try to invoke that same method,

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I get an error message. It says, hey, you can't call a method on a

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null valued expression. Big deal, I got an error.

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This does not necessarily mean that it's a bad thing. The fact that

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I got an error is something that actually I can work within

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PowerShell, and I can handle that exception.

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However, in Powershell 7,

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we now have an alternative, and that is to use this ?. operator.

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So the way this works is I reference the variable, and I'm putting the

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variable inside curly braces to isolate the variable name because

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technically, variable names could include a question mark,

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and I need to isolate that.

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So I have the variable name,

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$p, and then the operator, ?., and then I'm invoking

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the method. When I use this operator,

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I don't get an error, instead I get a null value.

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So you can see I just got a prompt back. And we can

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combine these null‑related operators.

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So here I'm going to use the ?? operator.

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Remember, if the left side of the operation is null,

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then use the value that is on the right side of the ??. So

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we already know that using the conditional null‑conditional

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operator is going to be null,

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which means I'm going to get the result, method failed, and that string will

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be written to the pipeline, and that gets assigned to $var.

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So, PowerShell is running the ?? expression and then returns that result,

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and that's what gets assigned to the variable $var.

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And so if I look at that,

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I get obviously the message that I'm expecting, method failed.

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You're more likely to use all these null‑related operators in

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PowerShell scripting than in the day‑to‑day basis in the PowerShell

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console, but I wanted you to see what they are and so you can get a feel for what they look like.