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Another option that we have within PowerShell is what's

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referred to as a switch statement.

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So what are switch statements?

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Well,

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they are an alternate syntax for doing multiple

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comparisons with a single or multiple values.

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The result of an expression will then get compared into each

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of those switch statements or conditions.

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If a value matches, then the matching code block can then be executed.

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Now the statement itself, there's a default statement,

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which is the optional dropout. So let's go back and

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talk about if and else for a second.

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If we have an if statement with an else, that else is the default.

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A switch statement also has an equivalent of that else option,

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which is the default dropout.

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So if nothing matches, it always goes to that default statement.

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The test expression can be a logical or an integer expression because

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obviously we're matching a value against something. And then,

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of course,

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we can use break statements at any point to basically

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terminate any of the code execution, and that's actually quite common.

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So, for example,

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if we have a switch statement with six different values to match against

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one of those matches, then we break the statement,

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which means we come out of that switch loop and then we

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continue on with the rest of our execution.

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Now the switch statement contains specific components.

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The first one is the initial test expression.

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So what is it that we're testing for?

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What's the output? Is it a number?

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Is it a value that's being calculated, something else? Then,

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of course, underneath that, we then have conditions that we need to match,

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which is the switch statements themselves.

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Now the syntax for this looks very straightforward.

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You can see it starts with the word switch, and the expression is

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the evaluation that we're trying to get to.

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Then underneath that, we have the list of conditions,

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the ones that we're trying to match.

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So if we were to write this out as actual PowerShell,

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we would have a number of variable where it's equal to 3.

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So that gives me my variable that I wish to test.

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And then my switch statement is going to take that number.

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Now what's different here is in the switch option, you can see that

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we're using parentheses with the word number.

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Now in an if statement, that's going to match if that

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contains something. Whereas in the switch world,

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we're basically saying in this statement,

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that is the number or the object I wish to test.

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Then underneath it, you can see what looks like very

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strange kind of outlay where we have 5, 10,

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20, and default; 5 and 10 and 20 are the comparison

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operators or the values that we've chosen.

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So I want to see if the number 3 matches number 5, number 10, number

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20, which obviously, in this instance, it won't.

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It will then drop into the default option, which will then execute the code.

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So a switch statement is really a different way of doing multiple if

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and else/if statements. Now the switch statement syntax itself has a

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test expression, which can combine operators.

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It provides support for multiple expression tests.

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So if you're trying to check it,

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you can say check it against this and this. And then the output

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can be from multiple comparison code paths.

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So what does that really mean?

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Well, if we were to use multiple switch statements,

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the code would look like this.

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Let's say we have two expressions that we're trying to validate. So it says

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Switch evaluation1, evaluation2, and then our execution paths,

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which are our conditions.

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So what does that look like?

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So let's say we have two variables, number 1, number 2, value of 5, value of 11.

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Go back to our same code. Now notice, the start of the switch

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statement now contains two variables. So we're now going to pass

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both of those values into the switch statement.

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Now what's different here compared to an if/else is an if and an

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else and else/if statement is basically saying,

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well, if this value did something,

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then do this. Whereas in the switch statement, we're able to pass

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in multiple expressions, and each of those expressions gets

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evaluated against the list of switches.

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So when I run it through, number 1 would go first,

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which is set to 5. So it would pass that line that

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says Write‑Host Number equals 5.

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Number 2 evaluation that would then run would drop out of all three into the default option and then write the message out.