1 00:00:00,510 --> 00:00:05,460 What would your friends in this lesson, we're going to understand loupe concepts in Python. 2 00:00:05,970 --> 00:00:06,930 So let's get started. 3 00:00:08,510 --> 00:00:10,220 So what are these loops? 4 00:00:11,240 --> 00:00:17,450 Well, loops are statements that make code run repeatedly, as the name may imply. 5 00:00:18,260 --> 00:00:20,690 So in general, statements are executed sequentially. 6 00:00:20,720 --> 00:00:21,020 Right. 7 00:00:21,350 --> 00:00:25,040 The first statement in a function is executed first, followed by the second and so on. 8 00:00:29,320 --> 00:00:33,910 There may be a situation when we need to execute a block of code, several numbers of times. 9 00:00:34,360 --> 00:00:39,790 Now, at that point, a loop statement will allow us to execute a statement or a group of statement 10 00:00:40,120 --> 00:00:41,200 multiple times. 11 00:00:43,220 --> 00:00:48,290 Now there are two kinds of loob statements while loops and for loops. 12 00:00:49,580 --> 00:00:51,530 So let's start with a while loops. 13 00:00:53,030 --> 00:00:59,480 While loops will allow us to repeat one or more actions while a condition remains true. 14 00:01:02,400 --> 00:01:09,120 So on a condition becomes false, program control passes to the line immediately following the loop. 15 00:01:10,360 --> 00:01:11,640 Have a look and see how that works. 16 00:01:12,540 --> 00:01:16,620 So let's define a variable name eye and print it. 17 00:01:16,620 --> 00:01:17,180 Repeat it. 18 00:01:18,090 --> 00:01:19,350 I equals zero. 19 00:01:19,950 --> 00:01:22,410 While I is less than 15. 20 00:01:30,990 --> 00:01:32,250 Print I. 21 00:01:37,480 --> 00:01:38,950 I plus equals one. 22 00:01:40,480 --> 00:01:48,700 So here we define the eye variable's value zero and we created a while loop and the loop printed the 23 00:01:48,700 --> 00:01:51,280 eye values from zero to 15. 24 00:01:51,460 --> 00:01:53,980 And then our loop ended after reaching 14. 25 00:01:55,240 --> 00:02:00,220 Now try to print Hello World 20 times I equals zero. 26 00:02:00,640 --> 00:02:02,920 While I was less than 20. 27 00:02:08,010 --> 00:02:09,660 Print Hello, world. 28 00:02:18,570 --> 00:02:20,280 I plus equals one. 29 00:02:22,440 --> 00:02:29,670 As you can see that our loop will work a while and then it stops because we defined a limit and every 30 00:02:29,670 --> 00:02:34,440 time it reruns after, our eye value will increase by one. 31 00:02:35,220 --> 00:02:37,530 So when it reaches that limit, it stops. 32 00:02:39,270 --> 00:02:42,870 So what if our eye value doesn't increase? 33 00:02:44,010 --> 00:02:44,850 Well, let's have a look. 34 00:02:45,540 --> 00:02:48,690 Eye equals zero while eye is less than 20. 35 00:02:54,900 --> 00:02:55,740 Print I. 36 00:03:08,620 --> 00:03:09,430 Oh, boy. 37 00:03:10,390 --> 00:03:14,380 As you can see, our loop will not stop and yeah, it will run forever. 38 00:03:14,870 --> 00:03:18,760 And that's why it's called an infinite loop or endless loop. 39 00:03:20,320 --> 00:03:21,400 So there you go. 40 00:03:21,400 --> 00:03:27,040 If you do try to run this code, then you've got to be able to click the interrupt the kernel here. 41 00:03:33,170 --> 00:03:35,900 And then click restart at the kernel here. 42 00:03:37,430 --> 00:03:42,240 OK, the colonel has restarted now and Jupiter's back working again. 43 00:03:43,710 --> 00:03:47,640 So as you just saw and maybe you did, maybe you didn't try it on your own. 44 00:03:48,240 --> 00:03:55,680 If we don't increment the variable I the value of the variable I remains constant zero and the loop 45 00:03:55,680 --> 00:03:57,090 condition remains constant. 46 00:03:57,120 --> 00:03:57,630 True. 47 00:03:58,500 --> 00:04:04,020 So then Python will print the eye variable repeatedly until we stop the kernel. 48 00:04:05,970 --> 00:04:07,500 Now we can talk about our other. 49 00:04:10,470 --> 00:04:17,040 The four statement allows you to repeat an action or several actions for each item in a sequence of 50 00:04:17,040 --> 00:04:17,460 items. 51 00:04:18,210 --> 00:04:22,730 For example, a string is a sequence of individual characters, right. 52 00:04:23,550 --> 00:04:24,750 So why don't we see how it works? 53 00:04:25,790 --> 00:04:27,290 Four characters in Python. 54 00:04:34,830 --> 00:04:36,270 Print character. 55 00:04:40,770 --> 00:04:48,300 Upon entering the statement, it signs the pea and python to the target variable between keywords for 56 00:04:48,450 --> 00:04:49,320 and in. 57 00:04:50,040 --> 00:04:51,420 In this case, character. 58 00:04:52,640 --> 00:04:56,600 And after executing the code, Python assigns to character. 59 00:04:56,840 --> 00:05:04,850 The next item in the sequence that is the Y in Python, then it executes the code again, and then this 60 00:05:04,850 --> 00:05:05,700 will continue. 61 00:05:05,720 --> 00:05:09,230 While there are more items in the sequence to process. 62 00:05:10,160 --> 00:05:14,840 So in this case, the statement terminates after displaying the letter N. 63 00:05:17,100 --> 00:05:20,400 So now let's talk about some fundamental stuff and loops. 64 00:05:21,810 --> 00:05:23,200 Maybe you have this question. 65 00:05:23,670 --> 00:05:31,290 So what should we do if we want to exit before the loop is complete or we want to change the loop flow? 66 00:05:32,740 --> 00:05:36,220 Well, in Python, we can do that with a control statement. 67 00:05:37,550 --> 00:05:44,660 Loop control statements change execution from its normal sequence, so when execution leaves a scope, 68 00:05:45,020 --> 00:05:49,040 all automatic objects that were created in that scope are destroyed. 69 00:05:50,480 --> 00:05:52,640 Python supports the following control statements. 70 00:05:53,880 --> 00:05:57,840 Break statement, continue statement and pass statement. 71 00:05:59,660 --> 00:06:01,820 So our first control statement is break. 72 00:06:02,030 --> 00:06:05,780 It is most commonly used statement by programmers and loops. 73 00:06:06,650 --> 00:06:10,220 So with the help of this statement, we can interrupt an ongoing process. 74 00:06:10,910 --> 00:06:14,450 Thus, the cycle is terminated without being bound to any condition. 75 00:06:21,080 --> 00:06:23,750 For example, number equals zero. 76 00:06:29,450 --> 00:06:31,910 While no, this is less than 15. 77 00:06:40,560 --> 00:06:41,280 Print, no. 78 00:06:48,390 --> 00:06:50,370 No plus equals one. 79 00:06:54,470 --> 00:06:55,580 Now we know this loop, right? 80 00:06:56,270 --> 00:06:58,340 So let's use a break statement. 81 00:06:58,640 --> 00:07:01,640 Number equals zero, while number is less than 15. 82 00:07:09,440 --> 00:07:10,190 Print, no. 83 00:07:14,900 --> 00:07:17,240 If I equals nine. 84 00:07:23,550 --> 00:07:24,090 Break. 85 00:07:27,030 --> 00:07:28,890 Number plus equals one. 86 00:07:30,900 --> 00:07:36,540 And as you can see, when the number variable's value reaches nine, the loop stopped and terminated. 87 00:07:37,470 --> 00:07:43,230 The most common use for a break is when some external condition is triggered, requiring a hasty exit 88 00:07:43,230 --> 00:07:43,710 from a loop. 89 00:07:44,880 --> 00:07:48,810 Also, the brake statement terminates only the loop in which it exists. 90 00:07:49,260 --> 00:07:55,800 So if there are other nested loops and a brake is used in the innermost loop, only that innermost loop 91 00:07:55,800 --> 00:07:56,400 ends. 92 00:07:59,170 --> 00:08:01,240 So our second statement is continue. 93 00:08:03,200 --> 00:08:10,430 The task of the continue statement is to ensure that everything that follows is Skift and then return 94 00:08:10,430 --> 00:08:11,270 to the beginning of the loop. 95 00:08:12,380 --> 00:08:15,560 So let's look at our examples to understand the continuous statement. 96 00:08:16,460 --> 00:08:17,420 No equal zero. 97 00:08:23,070 --> 00:08:25,050 While number is less than 10. 98 00:08:31,720 --> 00:08:33,100 If no equals to. 99 00:08:34,080 --> 00:08:35,400 Number plus equals one. 100 00:08:37,080 --> 00:08:37,680 Continue. 101 00:08:39,510 --> 00:08:40,650 Print, no. 102 00:08:45,200 --> 00:08:46,550 Number plus equals one. 103 00:08:53,480 --> 00:08:55,310 The result is, as you see. 104 00:09:01,840 --> 00:09:04,510 So our last control statement is pass. 105 00:09:05,950 --> 00:09:10,120 So we use pass when a statement is required syntactically. 106 00:09:10,630 --> 00:09:13,960 But you don't want any commander code to execute. 107 00:09:14,920 --> 00:09:17,590 So the past statement is a null operation. 108 00:09:17,980 --> 00:09:19,810 So nothing happens when it executes. 109 00:09:20,530 --> 00:09:22,480 Generally, we use it as a placeholder. 110 00:09:23,260 --> 00:09:24,220 I'll give you an example. 111 00:09:34,510 --> 00:09:37,870 And when we run this code, Python returns an error. 112 00:09:39,100 --> 00:09:40,240 But let's try with Pat. 113 00:09:41,900 --> 00:09:43,580 For character in Python. 114 00:09:51,850 --> 00:09:52,330 Part. 115 00:09:53,690 --> 00:09:56,870 And now you see that we don't get errors in our code. 116 00:09:59,840 --> 00:10:04,850 So now we'll talk about one more topic in this lesson, and it's the range function. 117 00:10:05,630 --> 00:10:08,150 So what is the range function? 118 00:10:10,840 --> 00:10:13,480 It's a predefined function in Python. 119 00:10:14,200 --> 00:10:17,470 It creates a structure based on the values that we give it. 120 00:10:18,940 --> 00:10:26,620 This structure creates a sequence of numbers that is similar to lists starting ending and optionally 121 00:10:26,680 --> 00:10:27,430 incrementing. 122 00:10:28,450 --> 00:10:33,400 So in Python, we can use the range function to represent numbers within a certain range. 123 00:10:33,910 --> 00:10:35,170 So when we see how it works. 124 00:10:36,040 --> 00:10:38,290 Range zero 15. 125 00:10:43,470 --> 00:10:49,680 And of course, when we run this code, it creates a sequence of numbers from zero to 15 and 15 is not 126 00:10:49,680 --> 00:10:50,280 included. 127 00:10:51,150 --> 00:10:54,810 So if we want to print this sequence, we can use the asterisk. 128 00:10:56,150 --> 00:10:56,570 Print. 129 00:10:58,970 --> 00:11:01,160 Asterisk range 015. 130 00:11:06,240 --> 00:11:14,700 It creates a sequence of numbers from zero to 15 and 15 is not included in the range function is a function 131 00:11:14,700 --> 00:11:17,130 that will take three different parameters. 132 00:11:18,740 --> 00:11:23,360 Now, we know that if the first parameter is zero, we don't need to specify it. 133 00:11:30,900 --> 00:11:36,780 However, if we are going to use the third parameter in the range function, that is to give a command 134 00:11:36,780 --> 00:11:42,990 like range zero 10 to, we have to specify all three parameters. 135 00:11:44,190 --> 00:11:51,780 So this will create numbers from three to 30 by giving for print answers range 334. 136 00:11:57,580 --> 00:12:04,060 Now, if we do not specify all the parameters here, Python cannot understand which number corresponds 137 00:12:04,060 --> 00:12:09,400 to which parameter range three, 10, five, five. 138 00:12:12,730 --> 00:12:18,490 So when we run this code, Python gives us an error and says range expected at most three arguments. 139 00:12:18,780 --> 00:12:19,690 And we got four. 140 00:12:21,130 --> 00:12:27,280 So now let's employ the structure that we created with the range function, with the for loop. 141 00:12:27,580 --> 00:12:31,000 Did I steal your idea for number in range? 142 00:12:34,790 --> 00:12:36,230 Zero 15. 143 00:12:40,490 --> 00:12:41,690 Print, no. 144 00:12:45,530 --> 00:12:46,040 That's it. 145 00:12:47,860 --> 00:12:53,830 All right, so in this lesson, we have learned the basic things that we need to know about lubes and 146 00:12:53,830 --> 00:12:54,970 range functions. 147 00:12:56,020 --> 00:12:59,500 Also, we've learned about how to control the loops with control statements. 148 00:12:59,650 --> 00:13:03,460 So in our next lesson, we're going to learn some other data types in Python. 149 00:13:03,940 --> 00:13:04,750 Want to see you there. 150 00:13:05,380 --> 00:13:06,130 Have a nice day.