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Appending Arrays in C# is a bit different than in other programming languages.

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25 - Appending Arrays.docx
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Quick reference

Appending Arrays

Arrays may be appended when you want to add something to the end.

When to use

Use this method to append an array.

Instructions

using System.Linq;

string[] toppings = new string[3] {"Pepperoni", "Mushroom", "Onion"};

toppings = toppings.Append("Green Peppers").ToArray();

Console.WriteLine(toppings[3]);

Hints & tips

  • Don't forget to import:  using System.Linq;
  • toppings = toppings.Append("Green Peppers").ToArray();
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  • 00:04 Okay, in this video I want to talk about appending arrays.
  • 00:06 And this is a touchy subject because I told you a couple of videos ago,
  • 00:10 we have to be very specific when we create our arrays.
  • 00:13 You can see right here, we're saying, hey,
  • 00:15 we're going to put three things in this array.
  • 00:17 And I come from a Python background and this just rubs me the wrong way because in
  • 00:21 Python you don't have to tell it how many things you're going to put into array.
  • 00:24 You can slap something on the end, you can remove things, you can change all around
  • 00:29 whenever you want, and it's very easy, not so much with C sharp.
  • 00:32 So like I said, in this video we're going to talk about appending array, so
  • 00:36 here we've got 0, 1, 2 items, so three items in total.
  • 00:40 Let's try and add something to the end of this.
  • 00:42 So let's go toppings and we know 0, 1, 2.
  • 00:47 So let's try to add something at position three.
  • 00:50 Now we've said there's only three items and
  • 00:53 here we're trying to add a fourth item.
  • 00:55 And now this is a little weird because three represents the fourth item,
  • 00:59 because again, arrays start at zero.
  • 01:01 So to add a fourth item it would be toppings three and
  • 01:05 here it let's just call this what, peppers like that, I don't know.
  • 01:09 So let's come down here and actually we could just copy this guy,
  • 01:13 put them in there, save this, run it, what do you think is going to happen?
  • 01:17 Angry, everything is orange and there are errors everywhere and
  • 01:22 the whole thing is just come crashing down, not good.
  • 01:25 So let's go ahead and close this out and what's going on here.
  • 01:28 Well, like I said,
  • 01:29 you've to explicitly say how many items are going to be in your array.
  • 01:33 You try to add one more, or 5 more, or 100 more, or a million more, you got problems,
  • 01:37 it just doesn't work.
  • 01:38 So C# expects there to be 3 things in this array and that's all there is to it.
  • 01:43 Now there's several different ways you can get around this.
  • 01:46 There are things called lists that we're not really going to talk about right now.
  • 01:49 You can create new arrays.
  • 01:51 You can take your stuff from your old array, add it to a new array where
  • 01:55 you've defined it to have more items in it, all kinds of things.
  • 02:00 I'm going to do something that's much easier.
  • 02:01 We're going to come up here to the top here, and
  • 02:05 we're going to call using a System.Linq, and this is L-I-N-Q.
  • 02:10 And this will allow us to sort of pseudo append something to our array.
  • 02:16 So here we can come down here and let me just comment this out.
  • 02:20 So what we can do is, we can take our toppings and
  • 02:25 we can set that equal to toppings.Append.
  • 02:29 And let's say we want to add green peppers, right?
  • 02:33 And then we want to go .ToArray and that's a function, and that should work.
  • 02:39 So, technically we're kind of creating a new array and adding this to it sort of.
  • 02:45 It's an empty sort of thing.
  • 02:46 Now here we can see, we're going to keep the third item here.
  • 02:50 So 0, 1, 2, 3 and this should work.
  • 02:53 Let's go ahead and save this and run it.
  • 02:57 And we see sure enough green peppers.
  • 02:59 Now we can also come down here, and let's console logout.Length.
  • 03:05 So up here before we append this, I'm going to console logout the length, and
  • 03:10 we're going to add something and look at the length again.
  • 03:14 So if we save this and run it.
  • 03:17 We see 3 green peppers and then 4.
  • 03:21 Now originally of course, we had 3 and then we added green peppers.
  • 03:25 So now the length of the array is 4, it has been changed.
  • 03:28 It has been appended and that's how we do that.
  • 03:30 So a little bit sloppy,
  • 03:31 at least a little sloppier than some of the other programming languages out there.
  • 03:35 But this will get the job done.
  • 03:36 Just remember to use System.Linq,
  • 03:39 that allows us to use this data pin thing to this array.
  • 03:44 And then we can add anything we want just like this.
  • 03:46 So that's all for this video.
  • 03:47 In the next video, we're going to look at multidimensional arrays.

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