1 00:00:02,940 --> 00:00:06,860 There's a lot that we can do with arrays and a lot of things for me to show you, 2 00:00:06,860 --> 00:00:08,620 so let's jump back into the console, 3 00:00:08,620 --> 00:00:14,460 and let me demonstrate a number of ways of working with arrays in PowerShell. 4 00:00:14,460 --> 00:00:18,920 Working with arrays in PowerShell, really not that difficult. 5 00:00:18,920 --> 00:00:23,340 Let me walk you through a few things so you can see these things in action. 6 00:00:23,340 --> 00:00:25,980 I'm going to begin by creating a variable, 7 00:00:25,980 --> 00:00:29,640 $a, and give it the values 1 through 10. 8 00:00:29,640 --> 00:00:32,380 I'm using the range operator, the dot dot (..), 9 00:00:32,380 --> 00:00:36,580 and $a, if I I look at it, has the values 1 through 10. 10 00:00:36,580 --> 00:00:38,800 PowerShell will automatically expand the array. 11 00:00:38,800 --> 00:00:44,340 You don't have to do anything special, just access the variable. 12 00:00:44,340 --> 00:00:47,610 Now I can also test if $a is an array. 13 00:00:47,610 --> 00:00:50,130 Now we're going to look at this operator later in the course, 14 00:00:50,130 --> 00:00:53,650 but this is a way to test if an object is of a certain type, 15 00:00:53,650 --> 00:00:57,170 and technically an array is a specific .NET type, 16 00:00:57,170 --> 00:00:58,590 and this returns true. 17 00:00:58,590 --> 00:01:00,480 So it is an array. 18 00:01:00,480 --> 00:01:05,160 And this object has a property that you might want to use called count. 19 00:01:05,160 --> 00:01:07,490 And this will tell you how many items are in the array. 20 00:01:07,490 --> 00:01:09,890 And so in this case, obviously, there are 10. 21 00:01:09,890 --> 00:01:13,500 Now even though I just showed you that $a is an array object, 22 00:01:13,500 --> 00:01:16,370 really, what is in the array, that is what matters. 23 00:01:16,370 --> 00:01:25,140 If I pipe $a to Get‑Member, you can see that the results are Int32 or numbers. 24 00:01:25,140 --> 00:01:26,890 Let's look at this another way. 25 00:01:26,890 --> 00:01:31,040 Let's create another variable, $b. 26 00:01:31,040 --> 00:01:34,360 And I'm going to add some string values to it. 27 00:01:34,360 --> 00:01:38,440 And let's see how many are in there, and I've got 5. 28 00:01:38,440 --> 00:01:40,350 So now what I want to do is I'm going to show you how to 29 00:01:40,350 --> 00:01:47,290 access individual elements of an array, and we do this by counting from 0, 30 00:01:47,290 --> 00:01:49,640 the index count. 31 00:01:49,640 --> 00:01:53,250 And so you can reference an individual element of an array by 32 00:01:53,250 --> 00:01:56,620 putting that index number in square brackets. 33 00:01:56,620 --> 00:02:02,040 So $b[0] is foo. 34 00:02:02,040 --> 00:02:06,040 One, which would be the next item in the list, obviously is bar. 35 00:02:06,040 --> 00:02:10,460 And you can also start at the end, and you can do that by using ‑1, 36 00:02:10,460 --> 00:02:12,980 which will give you the last item in the array. 37 00:02:12,980 --> 00:02:14,070 And you can go backwards. 38 00:02:14,070 --> 00:02:17,500 So I can do ‑2 and so on. 39 00:02:17,500 --> 00:02:20,230 Or you can also use a range operator here and say, 40 00:02:20,230 --> 00:02:23,270 Hey, get me the elements 1 through 3, remember, 41 00:02:23,270 --> 00:02:28,540 always starting counting at 0, and there PowerShell does that. 42 00:02:28,540 --> 00:02:31,540 All right, let's create an empty array. 43 00:02:31,540 --> 00:02:34,040 So I'm going to initialize an array $c, 44 00:02:34,040 --> 00:02:37,570 and we do that with the at symbol and two parentheses‑‑@(). 45 00:02:37,570 --> 00:02:39,710 Now I'm going to add some items to the array, 46 00:02:39,710 --> 00:02:42,780 and we do this with the += operator. 47 00:02:42,780 --> 00:02:46,440 So I'm going to add the string localhost. 48 00:02:46,440 --> 00:02:49,370 And then I'm going to add the environmental 49 00:02:49,370 --> 00:02:51,530 variable for the local computer name. 50 00:02:51,530 --> 00:02:57,940 And then I'm going to add another server name that I know is not on my network. 51 00:02:57,940 --> 00:02:58,940 So what's in $c? 52 00:02:58,940 --> 00:03:01,620 And we see three computer names. 53 00:03:01,620 --> 00:03:05,210 Now I show this to you because this is an example of how you 54 00:03:05,210 --> 00:03:07,720 might want to use arrays in PowerShell. 55 00:03:07,720 --> 00:03:11,140 You see a command in PowerShell called Test‑WSMan, 56 00:03:11,140 --> 00:03:13,630 which can be used to test if PowerShell remoting is enabled. 57 00:03:13,630 --> 00:03:16,540 And you say, Hey, it'll take a list of computer names. 58 00:03:16,540 --> 00:03:19,300 Well, I have computer names here, so let me try that. 59 00:03:19,300 --> 00:03:25,440 So I do Test‑WSMan and then do $c, and it fails. 60 00:03:25,440 --> 00:03:31,540 So I look at the Test‑WSMan cmdlet and look at that ‑ComputerName parameter. 61 00:03:31,540 --> 00:03:34,480 PowerShell tells me that this takes a System.String, 62 00:03:34,480 --> 00:03:39,860 and the way that it's written there means it only takes a single string. 63 00:03:39,860 --> 00:03:43,050 It can't handle an array of strings. 64 00:03:43,050 --> 00:03:43,860 Not to worry. 65 00:03:43,860 --> 00:03:46,560 Let's look at another network testing cmdlet. 66 00:03:46,560 --> 00:03:52,840 And let's test‑connection, which has a ‑TargetName parameter. 67 00:03:52,840 --> 00:03:55,930 Now here's the difference, and this is what I wanted to show you. 68 00:03:55,930 --> 00:03:58,660 The ‑TargetName parameter also takes strings, 69 00:03:58,660 --> 00:04:01,310 but notice that double‑square bracket. 70 00:04:01,310 --> 00:04:05,340 That indicates that you can pass multiple computer names 71 00:04:05,340 --> 00:04:08,720 all at the same time to this parameter. 72 00:04:08,720 --> 00:04:11,630 ‑ComputerName, up in Test‑WSMan, does not. 73 00:04:11,630 --> 00:04:14,140 It only takes a single string. 74 00:04:14,140 --> 00:04:15,920 -TargetName, in test‑connection, 75 00:04:15,920 --> 00:04:20,900 will take multiple computer names or multiple strings. 76 00:04:20,900 --> 00:04:25,520 And here's a quick look at what the command looks like. 77 00:04:25,520 --> 00:04:28,300 I'm just going to do a single ping to the localhost. 78 00:04:28,300 --> 00:04:31,210 So that's the object that I can expect. 79 00:04:31,210 --> 00:04:37,940 With that in mind then, I can create a PowerShell expression like this. 80 00:04:37,940 --> 00:04:42,610 So I'm going to do Test‑Connection, and I'm going to take all my computer names. 81 00:04:42,610 --> 00:04:46,540 I'm just pinging the IPv4 address just one time. 82 00:04:46,540 --> 00:04:48,580 Now every result that comes through is going to look like 83 00:04:48,580 --> 00:04:51,640 that object that we just looked at. 84 00:04:51,640 --> 00:04:55,060 And I'm going to filter with Where‑Object where the status of 85 00:04:55,060 --> 00:04:57,460 that incoming object is equal to success. 86 00:04:57,460 --> 00:05:03,050 For each result that I get, I'm going to do this. 87 00:05:03,050 --> 00:05:06,740 Now ForEach‑Object has a special way of working. 88 00:05:06,740 --> 00:05:09,290 Normally, we'd just do the ‑Process parameter, 89 00:05:09,290 --> 00:05:13,240 which is a script block that runs once for every object piped in. 90 00:05:13,240 --> 00:05:15,060 But there's also parameter ‑Begin, 91 00:05:15,060 --> 00:05:19,610 which is only run once before any pipeline input is processed. 92 00:05:19,610 --> 00:05:23,950 So I'm going to initialize an array, $c, in that block. 93 00:05:23,950 --> 00:05:29,830 In the ‑Process script block, I'm going to add the Destination property to $c, 94 00:05:29,830 --> 00:05:33,040 which will basically be the computer name. 95 00:05:33,040 --> 00:05:36,940 And then after I've processed everything, 96 00:05:36,940 --> 00:05:40,440 I'm going to just use write‑Host just to give me a little message to say, 97 00:05:40,440 --> 00:05:41,950 Hey, I finished testing. 98 00:05:41,950 --> 00:05:47,040 So we'll run that, pinging all the computers, 99 00:05:47,040 --> 00:05:47,560 filtering, 100 00:05:47,560 --> 00:05:51,660 and then only adding those that were successfully pinged 101 00:05:51,660 --> 00:05:56,700 to $c and then the end block runs, and I get my message that testing is complete, 102 00:05:56,700 --> 00:06:00,200 which means I can now look at $c and see, 103 00:06:00,200 --> 00:06:00,560 Okay, 104 00:06:00,560 --> 00:06:03,840 these are the computers that I was able to ping or that 105 00:06:03,840 --> 00:06:07,440 Test‑Connection was able to work with. 106 00:06:07,440 --> 00:06:11,700 There is a help topic you should look at to get more detail about arrays, 107 00:06:11,700 --> 00:06:13,120 help about_arrays. 108 00:06:13,120 --> 00:06:14,120 So you can see that there. 109 00:06:14,120 --> 00:06:19,000 I'm not going to scroll through that. I'll let you read that on your own.