1
00:00:00,610 --> 00:00:04,810
So when should you use a while loop and when should you use a for loop?

2
00:00:05,440 --> 00:00:08,830
And it really depends on the problem you're trying to solve.

3
00:00:09,700 --> 00:00:20,380
For example, in a for loop I could do for item in, let's say, a list, one, two, three.

4
00:00:20,830 --> 00:00:25,720
And just looking at this code, you know, right away that it's going to be looped over three times.

5
00:00:25,750 --> 00:00:26,110
Right.

6
00:00:26,900 --> 00:00:33,930
And I could say here, print item, but he can do this in a while loop as well.

7
00:00:34,870 --> 00:00:47,380
I can say I equals to zero, and then while I is less than, let's say, the length of the list, that

8
00:00:47,380 --> 00:00:49,030
is one, two, three.

9
00:00:50,230 --> 00:00:58,450
Well, in that case, I want you to print I or the item and then increment I by one.

10
00:01:00,950 --> 00:01:02,120
If I run this.

11
00:01:03,540 --> 00:01:08,940
I see that, well, technically here were incrementing the eye, which is the value, but let's say

12
00:01:08,940 --> 00:01:10,820
we had a list up here.

13
00:01:11,280 --> 00:01:15,590
So my list and this list will be one, two, three.

14
00:01:16,830 --> 00:01:24,690
Well, my list can be iterated with a for loop or can be iterated with a while loop.

15
00:01:24,690 --> 00:01:27,450
And we simply say my list.

16
00:01:28,500 --> 00:01:32,730
At index of I and if I run this.

17
00:01:34,430 --> 00:01:36,040
I get the same results.

18
00:01:37,800 --> 00:01:40,260
But which one do you think is better?

19
00:01:41,960 --> 00:01:49,750
First off, while loops are very flexible, we can do a lot because we have this conditional statement,

20
00:01:49,760 --> 00:01:52,700
we can loop more than three times if we really wanted to.

21
00:01:52,760 --> 00:01:57,980
So in that case, while loops are more powerful, but for loops are simpler, right.

22
00:01:57,980 --> 00:02:02,570
Like this code reads really nicely and really well, it makes sense.

23
00:02:02,580 --> 00:02:07,520
We just want to loop over something that we already know how many times we want to loop over three times

24
00:02:07,910 --> 00:02:08,810
with a wire loop.

25
00:02:08,810 --> 00:02:13,520
We have to create this variable and we have to make sure we remember to increment the variable so we

26
00:02:13,520 --> 00:02:14,840
don't get an infinite loop.

27
00:02:15,860 --> 00:02:20,450
So with a while loop, you need to make sure we remember to halt the loop at some point.

28
00:02:21,290 --> 00:02:29,150
So my rule is usually this for simple loops or iterating over iterable.

29
00:02:29,180 --> 00:02:31,520
Objects for loops are great.

30
00:02:31,880 --> 00:02:35,840
But let's say you're not sure how many times you want to loop over something.

31
00:02:36,020 --> 00:02:39,710
You're not really sure how long it's going to take.

32
00:02:40,600 --> 00:02:46,000
For looping, so you want to say while something is true, just keep looping.

33
00:02:47,010 --> 00:02:53,460
For example, let's say we're trying to go through an email list that we've collected on a website and

34
00:02:53,460 --> 00:02:56,660
for each email list, we want to send an email.

35
00:02:57,450 --> 00:03:03,420
Well, while the list is still there, let's just keep sending emails.

36
00:03:04,080 --> 00:03:11,040
There are many, many cases, but one of the most useful ways to use the while loop is like this.

37
00:03:13,750 --> 00:03:15,250
It's to say while.

38
00:03:18,640 --> 00:03:19,510
Do something.

39
00:03:21,150 --> 00:03:24,480
And make sure that at the end we break.

40
00:03:26,410 --> 00:03:28,120
Hold on, what's happening here?

41
00:03:29,140 --> 00:03:34,720
I'm saying, while true, wouldn't that create an infinite loop, I mean, true is always going to be

42
00:03:34,720 --> 00:03:37,560
true and you'd be right if you noticed that.

43
00:03:37,780 --> 00:03:40,030
But again, we have a brake statement here.

44
00:03:40,030 --> 00:03:44,170
So at the end, after we run line three, it's going to break.

45
00:03:45,310 --> 00:03:52,000
But now we can do something powerful like input here, and if you remember, an input is going to ask

46
00:03:52,000 --> 00:03:58,060
us for a prompt to enter something so I can say, hey, input, say something.

47
00:03:59,320 --> 00:04:00,700
And if I click run.

48
00:04:01,990 --> 00:04:06,880
It's going to say, hey, say something, you know, let's add semicolon here or call in here and let's

49
00:04:06,880 --> 00:04:08,800
try that again and look at that.

50
00:04:08,800 --> 00:04:13,120
It's saying say something, I'm on line three right now, so I'm going to say hi.

51
00:04:16,170 --> 00:04:20,490
And do you see that we just broke out of the loop?

52
00:04:21,270 --> 00:04:25,940
It only asked me once, even though this was true, as soon as we got to line four, I was done.

53
00:04:26,730 --> 00:04:28,770
But what if I remove this?

54
00:04:32,700 --> 00:04:41,370
If I say something, I say hi and then it asks me again, Hi, hi, I'm telling hi and it keeps asking

55
00:04:41,370 --> 00:04:42,540
me, asking me, asks me.

56
00:04:42,750 --> 00:04:44,970
And we have an infinite loop.

57
00:04:45,480 --> 00:04:49,350
But the interesting thing here is that we can use conditional logic.

58
00:04:49,350 --> 00:04:49,610
Right.

59
00:04:49,830 --> 00:04:50,790
What if we said.

60
00:04:51,880 --> 00:04:52,720
Response.

61
00:04:54,130 --> 00:05:05,680
Here and collect whatever the responses and say if response is equal to, let's say by then I'm going

62
00:05:05,680 --> 00:05:07,150
to break.

63
00:05:08,270 --> 00:05:10,250
So that if I run this again.

64
00:05:11,400 --> 00:05:17,070
I say he keeps asking me, and you know what, I'm getting annoyed with the machine, I'm going to say

65
00:05:17,070 --> 00:05:17,430
bye.

66
00:05:18,000 --> 00:05:20,540
It's going to exit it out for me.

67
00:05:21,270 --> 00:05:22,870
How cool is that?

68
00:05:23,550 --> 00:05:30,510
So while loops are extremely useful for tasks like this, where looping can happen for a long time,

69
00:05:30,510 --> 00:05:32,700
you don't know how many times it's going to happen.

70
00:05:32,970 --> 00:05:38,040
But this is something that you're just going to have to get used to with practice eventually.

71
00:05:38,190 --> 00:05:43,910
And I promise you, this happens where you'll figure out when to use while when to use for loop.

72
00:05:44,010 --> 00:05:47,250
But at the end of the day, use whatever solves your problem.

73
00:05:47,580 --> 00:05:48,490
I'll see you the next one.

74
00:05:49,050 --> 00:05:49,410
Bye bye.