1 00:00:01,800 --> 00:00:06,430 So I'm going to go ahead and write the four solutions for these four loops. 2 00:00:06,900 --> 00:00:09,990 So I'm going to make a new file save it. 3 00:00:09,990 --> 00:00:19,080 I'll just call it for loops that HMO and I'll just copy my setup from the while loops. 4 00:00:19,080 --> 00:00:20,460 So very similar. 5 00:00:20,460 --> 00:00:25,470 The only difference is I'm going to change the title to be for loops problem set and then I'm going 6 00:00:25,470 --> 00:00:32,340 to change the script to be for loops dot yes and then I'll make that file. 7 00:00:32,610 --> 00:00:41,190 So make a new file save it for loops dot J us and instead of here as I always like to do 8 00:00:44,010 --> 00:00:48,250 just put something so that we can tell that our loops are connected. 9 00:00:48,270 --> 00:00:50,010 So now if we go ahead and open that up 10 00:00:53,580 --> 00:00:56,560 tells us connected OK. 11 00:00:57,000 --> 00:00:59,230 So the very first problem was DePrince 12 00:00:59,350 --> 00:01:05,560 . 13 00:01:06,360 --> 00:01:12,000 So the very first problem is to print all the numbers between negative 10 and 19. 14 00:01:12,120 --> 00:01:18,360 So I'm going to copy the wild loop code that I have and move it over to four loops and I'm actually 15 00:01:18,360 --> 00:01:24,660 going to make this split screen so that you can see both happening at the same time. 16 00:01:24,660 --> 00:01:30,480 So I have my wild loop version on the left and then my FOR loop version on the right. 17 00:01:30,480 --> 00:01:35,390 So what I need to do is print all the numbers between negative 10 and 19. 18 00:01:36,030 --> 00:01:45,930 So for loop and then just do for I VAR I starts at negative 10 and we're going to keep running while 19 00:01:45,930 --> 00:01:47,620 I is less than 20. 20 00:01:48,110 --> 00:01:56,160 And then we're going to add one every time through the loop con. dog I and that's it. 21 00:01:56,160 --> 00:01:58,340 So it's substantially shorter. 22 00:01:58,350 --> 00:02:00,450 You don't have to make a separate variable. 23 00:02:00,480 --> 00:02:02,820 We don't need a separate line to increment the variable. 24 00:02:02,820 --> 00:02:04,670 We can do it all at once appear. 25 00:02:04,890 --> 00:02:09,430 So let's just make sure that works back to the browser refresh. 26 00:02:09,900 --> 00:02:16,600 Open up the console and we see negative 10 all the way to 19. 27 00:02:16,680 --> 00:02:22,650 So next up printing all the even numbers between 10 and 40. 28 00:02:22,710 --> 00:02:24,680 So there's a few ways we can do this. 29 00:02:24,720 --> 00:02:26,470 We can start we need four. 30 00:02:26,490 --> 00:02:31,790 Either way start i equal to 10 and we want to keep going. 31 00:02:32,070 --> 00:02:36,180 Well I is less than or equal to 40. 32 00:02:36,720 --> 00:02:38,530 So I'm just going to add some spaces. 33 00:02:38,550 --> 00:02:39,930 Technically it doesn't matter. 34 00:02:40,080 --> 00:02:42,200 I just like how it looks. 35 00:02:42,590 --> 00:02:46,130 And then every time through we can either add two. 36 00:02:46,200 --> 00:02:47,580 So I plus two equals two 37 00:02:51,210 --> 00:02:51,990 and that's it. 38 00:02:52,050 --> 00:02:53,470 Contador log I. 39 00:02:53,640 --> 00:02:56,040 And this is the first way of doing it. 40 00:02:56,790 --> 00:03:05,080 And just to demonstrate that back here refresh and we get all the even between 10 and 40. 41 00:03:06,780 --> 00:03:11,970 But again the problem with this solution it's the same problem we had with the first while loop solution 42 00:03:11,970 --> 00:03:12,360 . 43 00:03:12,540 --> 00:03:16,550 If instead I wanted to print the evens between 11 and 40. 44 00:03:16,770 --> 00:03:18,370 I'm going to have a problem. 45 00:03:18,610 --> 00:03:23,190 And that's because I'm just adding to. 46 00:03:26,790 --> 00:03:31,900 And that's because I'm just blindly adding to no matter what the starting value is. 47 00:03:32,250 --> 00:03:34,830 So I'm getting the odd numbers this time. 48 00:03:34,830 --> 00:03:41,280 So if I wanted to refactor it to match the other version where we actually check if a number is even 49 00:03:41,610 --> 00:03:44,560 and needs to look like this I add one every time. 50 00:03:44,910 --> 00:03:49,240 And then I have an if statement and I say if the number is even. 51 00:03:49,320 --> 00:03:56,280 So if I had two equals zero then we'll come to that log. 52 00:03:56,280 --> 00:03:58,830 I just like that. 53 00:04:00,060 --> 00:04:05,940 And we shouldn't notice a difference very fresh still works just the same that this is the more foolproof 54 00:04:05,940 --> 00:04:10,280 way where I can change this to be an odd number and it still doesn't matter. 55 00:04:10,290 --> 00:04:15,820 Now it just prints the evens starting from 13 to 40. 56 00:04:15,830 --> 00:04:17,410 All right. 57 00:04:17,430 --> 00:04:24,240 The next one printing all the odd numbers between 300 and 333. 58 00:04:24,330 --> 00:04:26,380 So we want another for loop. 59 00:04:26,670 --> 00:04:31,070 We'll start i equal to 300. 60 00:04:31,170 --> 00:04:32,200 We want to keep going. 61 00:04:32,250 --> 00:04:41,870 Well I asked less than or equal to 3 3 3 and we'll just add one every time. 62 00:04:43,650 --> 00:04:48,810 And then what we'll do just like we did up here instead of checking if something is even Well check 63 00:04:48,810 --> 00:04:49,690 if it's odd. 64 00:04:49,860 --> 00:04:51,040 So it's very similar. 65 00:04:51,240 --> 00:04:59,100 If I my two is not equal to zero that means that it's odd it's not divisible by two then we'll cancel 66 00:04:59,100 --> 00:05:11,430 that log and say that refresh and we get all the odd numbers starting at 3 or 1 up to 3 133. 67 00:05:12,330 --> 00:05:19,770 So the very last one printing all the numbers divisible by five and three that are between five and 68 00:05:19,770 --> 00:05:20,740 50. 69 00:05:21,210 --> 00:05:25,950 So another for loop we start or I equal to five. 70 00:05:25,980 --> 00:05:33,230 We keep going while it's less than or equal to 50 and we add one at the end of every loop. 71 00:05:33,510 --> 00:05:38,490 Then what we're going to do is have an if statement check if I is divisible by five 72 00:05:41,460 --> 00:05:50,460 then we're going to check if it also divisible by three I like that. 73 00:05:50,460 --> 00:05:55,530 And then we cancel the log and that's it we're done. 74 00:05:55,530 --> 00:05:57,170 So let's check it out. 75 00:05:57,570 --> 00:06:01,990 Refresh and you can see we get 15 30 and 45. 76 00:06:02,400 --> 00:06:08,730 So to recap here on the left I have the while loop solutions and on the right I have the for loop solutions 77 00:06:09,030 --> 00:06:13,350 so I'll try and get them to match up as perfectly as possible 78 00:06:13,350 --> 00:06:20,760 . 79 00:06:20,760 --> 00:06:21,510 There we go. 80 00:06:21,900 --> 00:06:26,090 And you can see the for loop solutions are considerably shorter.