1 00:00:00,009 --> 00:00:04,539 Let's now go back to our trusty replit. And I'm gonna give you two examples. 2 00:00:04,550 --> 00:00:06,829 One for the for loop 3 00:00:07,199 --> 00:00:09,789 and another for the while loop. 4 00:00:10,050 --> 00:00:10,590 So 5 00:00:11,149 --> 00:00:15,920 in order to create our for loop, let's first of all, create the list in 6 00:00:16,370 --> 00:00:22,430 this case, right now, I'm going to provide the name of the list as names. OK? 7 00:00:22,889 --> 00:00:23,889 Equals 8 00:00:24,409 --> 00:00:27,950 and then I'm gonna have my brackets in here and let's add 9 00:00:28,559 --> 00:00:31,340 some names. So I've got uh Alex, 10 00:00:32,319 --> 00:00:35,259 I've got uh Nancy 11 00:00:36,860 --> 00:00:40,259 and I've got a James 12 00:00:41,130 --> 00:00:44,430 and let's say last, but not least 13 00:00:45,270 --> 00:00:46,060 I 14 00:00:46,189 --> 00:00:47,220 have got 15 00:00:48,069 --> 00:00:50,009 uh Violetta. 16 00:00:50,830 --> 00:00:52,369 Honestly, I just came up with that name, 17 00:00:53,139 --> 00:00:54,500 Violetta. OK. 18 00:00:54,750 --> 00:00:59,189 So we have our list right here of four different names, right? Alex, Nancy James. 19 00:00:59,200 --> 00:01:00,610 And then Violetta, 20 00:01:01,090 --> 00:01:05,589 one thing I can do right now is we can create a variable 21 00:01:05,849 --> 00:01:10,010 that will represent each item in the list. 22 00:01:10,019 --> 00:01:14,129 Kind of like how we've been assigning values to variables like X equals four, 23 00:01:14,139 --> 00:01:15,650 Y equals seven. 24 00:01:15,989 --> 00:01:19,129 I can now come in here and then simply say 25 00:01:19,360 --> 00:01:20,589 four, 26 00:01:21,319 --> 00:01:24,970 OK? And now I will say four X 27 00:01:26,940 --> 00:01:27,989 in 28 00:01:28,160 --> 00:01:29,389 names. 29 00:01:30,430 --> 00:01:31,029 OK? 30 00:01:31,559 --> 00:01:34,519 What this does right here and let me just add the colon right? There. 31 00:01:34,779 --> 00:01:38,620 So what we've done with this statement here is that we're saying, OK, 32 00:01:38,680 --> 00:01:42,849 we are going to use X to represent each 33 00:01:43,180 --> 00:01:50,430 name in this list. So X will be equal to Alex. That will be the first loop, that 34 00:01:50,599 --> 00:01:50,970 one, 35 00:01:51,250 --> 00:01:54,559 the second loop X will not be equal to Nancy. It will 36 00:01:54,660 --> 00:01:57,430 run, the third loop will not be X equals to James. 37 00:01:57,440 --> 00:02:00,519 And then finally, the very last loop will be X 38 00:02:00,650 --> 00:02:03,650 is equal to violet. And that's basically what this does in here. 39 00:02:03,660 --> 00:02:05,529 So we're saying for X in names 40 00:02:05,790 --> 00:02:10,949 and now we have to tell the program. OK. What should we do? Well, 41 00:02:11,940 --> 00:02:13,070 we should print out 42 00:02:14,350 --> 00:02:14,899 the name 43 00:02:15,919 --> 00:02:16,550 X. 44 00:02:18,690 --> 00:02:19,110 OK. 45 00:02:19,830 --> 00:02:21,570 I am going to run 46 00:02:22,020 --> 00:02:22,770 and there you go, 47 00:02:23,210 --> 00:02:24,449 Alex, 48 00:02:24,820 --> 00:02:27,710 Nancy, James and 49 00:02:28,169 --> 00:02:29,110 Violetta. 50 00:02:29,559 --> 00:02:32,789 But what if I wanted to spice this program up 51 00:02:32,800 --> 00:02:35,020 just a little bit and let's say something like, 52 00:02:35,029 --> 00:02:38,779 you know, good morning and then the name of that person. 53 00:02:38,789 --> 00:02:42,830 So we'll have Good morning, Alex, good morning, Nancy, good morning James. 54 00:02:42,839 --> 00:02:44,149 And of course, good morning 55 00:02:44,289 --> 00:02:45,149 Violetta. 56 00:02:45,419 --> 00:02:47,990 How are we going to do this? Well, 57 00:02:48,169 --> 00:02:50,710 inside of the print function, 58 00:02:51,210 --> 00:02:54,309 I am going to add a string that will first of all say 59 00:02:54,800 --> 00:02:56,509 good 60 00:02:56,639 --> 00:02:57,869 morning, 61 00:03:00,009 --> 00:03:00,550 okay. 62 00:03:01,330 --> 00:03:04,509 And then we're going to have the comma which by the 63 00:03:04,520 --> 00:03:07,830 way is just part of the actual print out itself. 64 00:03:07,839 --> 00:03:10,779 It's not part of the actual program. 65 00:03:10,789 --> 00:03:11,910 If you know what I mean, it's not, 66 00:03:11,919 --> 00:03:14,050 it's part of the string basically is what I'm trying to say, we can 67 00:03:14,160 --> 00:03:16,289 do so without the comma as well. 68 00:03:16,300 --> 00:03:19,470 In fact, you know what, let me remove the comma just so I don't confuse you. 69 00:03:19,559 --> 00:03:21,419 So I'm gonna say good morning. 70 00:03:21,660 --> 00:03:22,270 Ok? 71 00:03:22,639 --> 00:03:23,630 And then 72 00:03:24,110 --> 00:03:26,789 I am going to add a space 73 00:03:27,210 --> 00:03:30,449 because we want to be space between the actual string. 74 00:03:30,460 --> 00:03:32,130 Good morning and then the name of the person. 75 00:03:32,139 --> 00:03:34,110 That's why I've added the space right there. 76 00:03:34,449 --> 00:03:37,110 Ok? And then right here, 77 00:03:37,520 --> 00:03:39,830 I am going to add the plus sign 78 00:03:40,320 --> 00:03:41,500 and then X 79 00:03:42,169 --> 00:03:43,669 so basically attaching 80 00:03:43,839 --> 00:03:45,110 the string. Good morning 81 00:03:45,360 --> 00:03:47,509 to the name of the person. 82 00:03:47,800 --> 00:03:49,380 Let's run the program 83 00:03:49,869 --> 00:03:50,729 and there you go. 84 00:03:51,110 --> 00:03:54,580 Good morning, Alex. Good morning and good morning, James. Good morning, Violetta. 85 00:03:55,490 --> 00:03:58,330 Now, if I remove this space because I want you to understand this very well. 86 00:03:58,339 --> 00:04:01,710 If I remove this space right now and I run the program again, 87 00:04:01,960 --> 00:04:05,619 you can see right now that it's all jumbled up, 88 00:04:05,710 --> 00:04:07,759 there's no space between morning and then the name of the person. 89 00:04:07,770 --> 00:04:08,910 That's why once again, 90 00:04:09,139 --> 00:04:13,509 I added the space right here between the G and the closing quotation marks. 91 00:04:13,880 --> 00:04:14,520 So 92 00:04:14,759 --> 00:04:15,869 one more time 93 00:04:16,230 --> 00:04:17,048 and there you go. 94 00:04:17,290 --> 00:04:21,380 This is an example of a very simple for loop. 95 00:04:21,390 --> 00:04:26,750 First of all, we created a list of names, we assigned this entire 96 00:04:27,440 --> 00:04:29,950 list right here to the variable names. 97 00:04:30,170 --> 00:04:34,600 And then we now need to create another variable that will represent each item, 98 00:04:34,609 --> 00:04:36,220 each name in this list. 99 00:04:36,230 --> 00:04:39,410 So we said for X in 100 00:04:39,579 --> 00:04:41,350 the list called names. 101 00:04:41,570 --> 00:04:43,500 And now the function print good morning 102 00:04:43,670 --> 00:04:48,829 plus the name of the person in that list. 103 00:04:48,970 --> 00:04:52,529 This is an example of your for loop. 104 00:04:53,040 --> 00:04:53,940 Now, 105 00:04:54,130 --> 00:04:55,839 what I'm gonna do is 106 00:04:55,959 --> 00:05:01,299 we're going to create a while loop now to do this. 107 00:05:01,920 --> 00:05:04,700 Let's come down here and yes, we can run 108 00:05:04,920 --> 00:05:08,820 multiple programs and functions within the exact same file. All right. 109 00:05:09,489 --> 00:05:09,910 So 110 00:05:10,640 --> 00:05:15,799 what I'm gonna do right now is I'm going to create something called a counter. 111 00:05:16,109 --> 00:05:17,299 OK? So counter 112 00:05:17,559 --> 00:05:19,019 equals zero. 113 00:05:19,480 --> 00:05:20,950 Now, what exactly am 114 00:05:21,070 --> 00:05:22,839 I doing here? What is this counter? 115 00:05:23,190 --> 00:05:26,519 Remember that with while loops, 116 00:05:26,959 --> 00:05:30,579 they will continue to run as long as a condition 117 00:05:30,730 --> 00:05:33,260 continues to be satisfied. 118 00:05:33,500 --> 00:05:37,179 That's the difference between a for loop and a while loop with the full loop. 119 00:05:37,320 --> 00:05:39,720 We have a list of items, right? So 120 00:05:39,850 --> 00:05:42,609 the loop will simply run through all the items in that list. 121 00:05:42,779 --> 00:05:46,950 But a wide loop, there has to be some sort of a condition 122 00:05:47,100 --> 00:05:48,600 that will be presented. 123 00:05:48,790 --> 00:05:50,929 And then we're gonna tell Python that, hey, 124 00:05:50,940 --> 00:05:56,279 as long as this particular condition continues to be satisfied, execute the loop. 125 00:05:56,579 --> 00:05:57,119 So 126 00:05:57,390 --> 00:06:02,239 the condition here right now is that while a counter 127 00:06:02,529 --> 00:06:04,720 is less than, let's say three, 128 00:06:06,130 --> 00:06:07,420 do you now see 129 00:06:07,679 --> 00:06:11,709 we're saying, hey, as long as our counter, 130 00:06:11,720 --> 00:06:15,040 as long as the number in here is less than three, 131 00:06:15,420 --> 00:06:20,630 continue to do something. And you can see Python kind of already given us a hint 132 00:06:20,859 --> 00:06:22,790 of where to go next. Well, 133 00:06:23,279 --> 00:06:24,890 I'm gonna say print, 134 00:06:25,410 --> 00:06:26,670 print and then 135 00:06:27,589 --> 00:06:29,559 I'm going to add a text right there, the string. 136 00:06:30,190 --> 00:06:31,570 Uh hello. 137 00:06:32,239 --> 00:06:32,739 Ok. 138 00:06:34,130 --> 00:06:34,820 And there you go. 139 00:06:35,519 --> 00:06:39,619 Now what we're saying here is, start from zero. 140 00:06:40,119 --> 00:06:45,600 Ok, start from zero and then check to see if zero is less than three. 141 00:06:45,609 --> 00:06:49,440 If it's less than three, then print. Hello. 142 00:06:49,929 --> 00:06:50,980 However, 143 00:06:51,329 --> 00:06:53,820 we're not actually done. 144 00:06:54,049 --> 00:06:54,980 Why? 145 00:06:55,369 --> 00:07:00,140 Well, because we haven't specifically told Python 146 00:07:00,519 --> 00:07:01,190 to 147 00:07:01,359 --> 00:07:02,070 add 148 00:07:02,440 --> 00:07:04,829 a new number to the counter. So 149 00:07:05,010 --> 00:07:07,470 instead of zero, it will not become one 150 00:07:07,630 --> 00:07:11,070 check to see if one is less than three and then print out. Hello. 151 00:07:11,380 --> 00:07:16,130 We haven't told Python that yet because a loop can go either way, 152 00:07:16,350 --> 00:07:18,070 we can either continue to add 153 00:07:18,600 --> 00:07:26,339 or 123 to 0 or we could go the opposite direction and then instead of zero going to one, 154 00:07:26,350 --> 00:07:30,910 it could be zero, going to minus one minus two minus three minus four. 155 00:07:31,119 --> 00:07:32,440 And in that kind of scenario, 156 00:07:33,279 --> 00:07:35,320 those numbers will always be less than 157 00:07:35,329 --> 00:07:39,299 three and the condition will never be satisfied 158 00:07:39,630 --> 00:07:42,679 or that it will always be satisfied rather. 159 00:07:42,880 --> 00:07:44,579 And then that will crush the program. 160 00:07:44,760 --> 00:07:48,059 So we need to tell Python explicitly that, hey, 161 00:07:48,359 --> 00:07:51,940 once you've run the very first loop where zero is less than three, 162 00:07:51,950 --> 00:07:54,230 add one to the counter. 163 00:07:54,390 --> 00:07:55,029 So 164 00:07:55,190 --> 00:07:57,579 I'm gonna come in right now and I'm gonna say counter 165 00:07:58,829 --> 00:07:59,589 and then 166 00:07:59,920 --> 00:08:02,720 plus equals one. 167 00:08:03,980 --> 00:08:06,920 This is our way of saying OK, Python 168 00:08:07,040 --> 00:08:10,369 the very first, the very beginning of the loop will be zero, 169 00:08:10,480 --> 00:08:14,399 check to see if zero is less than three, if it's less than three print. Hello. 170 00:08:14,519 --> 00:08:17,660 And then now add one to the counter. So it will not be one 171 00:08:18,179 --> 00:08:21,940 at less than three. Python says. Yes, one is indeed less than three. 172 00:08:21,950 --> 00:08:25,779 It's gonna print out. Hello. It's gonna add one again. So one will not become two. 173 00:08:25,790 --> 00:08:27,850 Python is gonna check. Ok. It's two, less than three. 174 00:08:27,859 --> 00:08:31,109 Yes, it's less than three print. Hello. And then it's gonna add one again. 175 00:08:31,119 --> 00:08:32,400 So to now becomes three. 176 00:08:32,780 --> 00:08:34,780 And then finally, Python will say that OK, 177 00:08:34,789 --> 00:08:38,849 three isn't less than three because three equals three and then it will end 178 00:08:39,000 --> 00:08:39,558 the loop. 179 00:08:40,760 --> 00:08:41,450 OK? 180 00:08:41,650 --> 00:08:45,159 Let's go ahead right now and run 181 00:08:45,590 --> 00:08:46,440 and there you go. 182 00:08:46,880 --> 00:08:48,729 Hello. Hello? Hello. 183 00:08:48,849 --> 00:08:51,099 You can see right there that it stopped at three 184 00:08:51,109 --> 00:08:53,200 loops because the very first loop will be for zero, 185 00:08:53,440 --> 00:08:57,080 second loop will be for one third loop will be for two 186 00:08:57,900 --> 00:08:59,130 if I came here. 187 00:08:59,309 --> 00:09:01,770 And I said, OK, less than seven 188 00:09:02,340 --> 00:09:03,400 run. 189 00:09:03,750 --> 00:09:11,659 Now, you can see we have again, 40123456 hellos. 190 00:09:12,130 --> 00:09:12,679 So 191 00:09:13,140 --> 00:09:14,419 that's the difference between 192 00:09:14,530 --> 00:09:16,599 the for loop and 193 00:09:16,710 --> 00:09:18,559 the while loop. 194 00:09:18,570 --> 00:09:23,109 You can see right now with the full loop, we have our list or our, our way 195 00:09:23,539 --> 00:09:25,960 and then the loop will go through each particular 196 00:09:25,969 --> 00:09:28,559 item in that way and it will do something. 197 00:09:28,880 --> 00:09:33,640 But for the while loop, we need to first of all specify what's the beginning point 198 00:09:34,109 --> 00:09:37,349 and then we will not provide the condition as long as this 199 00:09:37,359 --> 00:09:40,080 equals this or this is less than this or this is this, 200 00:09:40,830 --> 00:09:42,080 do something 201 00:09:42,369 --> 00:09:47,169 and then either add one or remove one or just do something 202 00:09:47,179 --> 00:09:50,390 to make sure that the loop will now actually begin to run. 203 00:09:50,679 --> 00:09:53,549 That's the difference between the for loop and the while loop. 204 00:09:53,559 --> 00:09:55,320 Of course, we're going to be working a lot more 205 00:09:55,440 --> 00:09:58,690 with four and wide loops in this course. But thank you for watching. 206 00:09:58,700 --> 00:10:00,510 I will see you in the next class.