1 00:00:00,040 --> 00:00:03,780 Now the most important way that people kind of catch these errors 2 00:00:03,780 --> 00:00:07,260 is by using what's referred to as the TRY/CATCH, 3 00:00:07,260 --> 00:00:10,440 TRY/CATCH/FINALLY statements. 4 00:00:10,440 --> 00:00:15,600 Now, of course, there are three of these, so the first one is a TRY/CATCH. 5 00:00:15,600 --> 00:00:20,150 This will try the section of code that you wish to execute, 6 00:00:20,150 --> 00:00:21,730 and if it throws an error, 7 00:00:21,730 --> 00:00:25,940 it will drop it into a catch where you can do something else. 8 00:00:25,940 --> 00:00:29,590 The TRY/FINALLY doesn't handle the error. 9 00:00:29,590 --> 00:00:33,910 It simply executes the code if the exception occurs. 10 00:00:33,910 --> 00:00:39,850 The TRY/CATCH/FINALLY will be the combination of throwing errors and 11 00:00:39,850 --> 00:00:43,400 executing code. So you don't have to use all of them. 12 00:00:43,400 --> 00:00:47,070 You can pick whichever one works for the script that you're 13 00:00:47,070 --> 00:00:50,470 writing. So if I want to generate an exception, 14 00:00:50,470 --> 00:00:51,990 I'm going to use our standard function. 15 00:00:51,990 --> 00:00:55,860 So a standard function of New‑Error Throw "This is an Error." 16 00:00:55,860 --> 00:00:59,040 That will cause me to have an exception. 17 00:00:59,040 --> 00:01:02,230 If I was to wrap this around in a TRY/CATCH, 18 00:01:02,230 --> 00:01:05,590 let's say I was calling that function, I could say try 19 00:01:05,590 --> 00:01:10,540 New‑Error, and if the new error caused an issue, 20 00:01:10,540 --> 00:01:11,970 I could then catch that, 21 00:01:11,970 --> 00:01:14,930 which is the next line down, and then it would write a 22 00:01:14,930 --> 00:01:17,840 value saying An Exception was Generated. 23 00:01:17,840 --> 00:01:21,820 So the try and the catch are very similar syntax to 24 00:01:21,820 --> 00:01:24,280 the loops that we were looking at, where we're, 25 00:01:24,280 --> 00:01:24,780 you know, 26 00:01:24,780 --> 00:01:28,490 saying an if and else or we're looping through something and saying 27 00:01:28,490 --> 00:01:32,490 if this else if else, or the same as a switch statement, which would 28 00:01:32,490 --> 00:01:37,660 be switch conditions and then a default. It's the same logic here. So 29 00:01:37,660 --> 00:01:39,940 we test something in the try. 30 00:01:39,940 --> 00:01:43,240 If it fails, we catch. 31 00:01:43,240 --> 00:01:46,150 If we were to change this to use the FINALLY, 32 00:01:46,150 --> 00:01:50,720 then what you can see is we have try and finally, it will go and 33 00:01:50,720 --> 00:01:52,850 say I'm using a function called New‑Message, 34 00:01:52,850 --> 00:01:55,440 which is going to write a message out, and it will say 35 00:01:55,440 --> 00:01:58,240 New‑Message finally Write‑Output. 36 00:01:58,240 --> 00:02:00,550 So if it continues to error, 37 00:02:00,550 --> 00:02:03,290 it will just capture the error but then drop down 38 00:02:03,290 --> 00:02:05,840 and carry on and execute the code. 39 00:02:05,840 --> 00:02:11,060 Now we could mix this all together and use the TRY/CATCH with the 40 00:02:11,060 --> 00:02:13,890 FINALLY. So you can see I'm calling my test, 41 00:02:13,890 --> 00:02:16,880 which is my New‑Message, which will have my throw code in it. 42 00:02:16,880 --> 00:02:19,630 It's going to throw the message an error. 43 00:02:19,630 --> 00:02:20,920 I'm then going to catch it, 44 00:02:20,920 --> 00:02:25,610 and it will write the value out. Now, depending on the logic here, 45 00:02:25,610 --> 00:02:31,040 it could either go to the catch or it would drop out to the finally. 46 00:02:31,040 --> 00:02:33,190 So depending on how you structure this, 47 00:02:33,190 --> 00:02:37,370 you can either catch it or you can go to the finally and write the message out. 48 00:02:37,370 --> 00:02:41,140 But we'll look at this one in a few minutes. 49 00:02:41,140 --> 00:02:45,450 We also have what's called typed exception handling available to us. 50 00:02:45,450 --> 00:02:50,790 So exceptions that have a specific type, you can specify the type of 51 00:02:50,790 --> 00:02:53,340 exception that you're trying to catch. 52 00:02:53,340 --> 00:02:55,620 So if it's a piece of string value, 53 00:02:55,620 --> 00:02:59,540 then you can say, This is the type of exception I wish you to catch. 54 00:02:59,540 --> 00:03:05,240 You can catch multiple exception types with a single TRY/CATCH statement. 55 00:03:05,240 --> 00:03:07,290 So what does that look like in reality? 56 00:03:07,290 --> 00:03:11,540 So I have a path here, so C:\Documents\Code. 57 00:03:11,540 --> 00:03:17,050 I do a try, and the try says New‑Error ‑Path, ‑ErrorAction Stop. 58 00:03:17,050 --> 00:03:19,440 So that's my initial try. 59 00:03:19,440 --> 00:03:20,800 If I go underneath that, 60 00:03:20,800 --> 00:03:23,900 I can then use the catch statement here, and notice what I'm 61 00:03:23,900 --> 00:03:27,830 doing. Instead of it just catching the error, I'm looking 62 00:03:27,830 --> 00:03:30,630 for specific types of errors. 63 00:03:30,630 --> 00:03:35,740 So I'm looking for DirectoryNotFound or FileNotFound, 64 00:03:35,740 --> 00:03:37,940 and then I'm going to write a value. 65 00:03:37,940 --> 00:03:42,930 If I go to the catch, I could also do just an IOException so it couldn't 66 00:03:42,930 --> 00:03:47,500 open the file. So we can now strongly type the catch. 67 00:03:47,500 --> 00:03:54,000 So instead of it catching every exception, it's only going to catch it if it matches that strongly typed configuration.