Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,280 --> 00:00:04,720 Now up to this point, you've seen us use if statements, 2 00:00:04,750 --> 00:00:06,460 else statements, elif statements, 3 00:00:06,610 --> 00:00:10,600 multiple if statements as well as nested if statements. 4 00:00:10,990 --> 00:00:15,990 But the thing that we haven't been able to do thus far is to check for multiple 5 00:00:16,780 --> 00:00:20,440 conditions in the same line of code. 6 00:00:21,250 --> 00:00:26,140 So how would we be able to combine different conditions and say, well, 7 00:00:26,200 --> 00:00:31,200 is the pizza large and the user wants pepperoni and extra cheese all in the 8 00:00:32,290 --> 00:00:34,510 same line of code? Well, 9 00:00:34,570 --> 00:00:37,900 to do this we would need to learn about the logical operators. 10 00:00:38,290 --> 00:00:42,280 So there's three of them that are really useful: and, or and not. 11 00:00:43,180 --> 00:00:44,830 So let's take a look at the first one. 12 00:00:45,280 --> 00:00:49,060 When you combine two different conditions using an and operator, 13 00:00:49,390 --> 00:00:51,310 they both have to be true, 14 00:00:51,310 --> 00:00:55,390 both A and B for the entire line of code to be true. 15 00:00:56,320 --> 00:00:59,920 If just one of them is true, say A is true and B is false, 16 00:00:59,920 --> 00:01:04,780 or A is false and B is true, then the overall thing evaluates to false. 17 00:01:06,070 --> 00:01:08,800 So if we take a look just inside the console, 18 00:01:08,830 --> 00:01:13,450 and in fact, I'm going to clear the console, and I write some code here. 19 00:01:13,480 --> 00:01:14,770 Let's say that, um, 20 00:01:15,250 --> 00:01:20,250 A = 12 right? Now let's say that I wanted to check whether if is A greater 21 00:01:23,320 --> 00:01:27,460 than 15? Well that is going to be false. 22 00:01:28,060 --> 00:01:32,410 Now what about is A greater than 10? Well, 23 00:01:32,410 --> 00:01:33,340 that's going to be true. 24 00:01:33,940 --> 00:01:38,680 Now if I combined this using an and statement, I could say, 25 00:01:38,680 --> 00:01:43,680 well is A greater than 10 and A is less than 13 and hit enter, then I would get 26 00:01:49,450 --> 00:01:54,450 true because both A is greater than 10 and A is less than 13 are true. 27 00:01:55,990 --> 00:01:58,660 So in this case, when both conditions are true, 28 00:01:59,110 --> 00:02:02,320 then this entire line gets evaluated to true. 29 00:02:02,950 --> 00:02:06,100 But see what happens when just one of them is false. 30 00:02:06,250 --> 00:02:11,250 So is A greater than 15 and A less than 13? A is greater than 15 is false, 31 00:02:13,960 --> 00:02:17,590 A is less than 13 is true and now we get false. 32 00:02:18,580 --> 00:02:23,470 So that's what happens when you combine different conditions using and. Now if 33 00:02:23,470 --> 00:02:26,650 you only needed one of the conditions to be true, 34 00:02:27,040 --> 00:02:29,980 then you could use the or operator instead. 35 00:02:30,160 --> 00:02:35,160 So if a C or D were true or if they're both true, 36 00:02:35,740 --> 00:02:37,240 then it'll evaluate to true. 37 00:02:38,110 --> 00:02:41,680 It's only when both C and D are false 38 00:02:42,130 --> 00:02:44,530 does this statement actually become false. 39 00:02:45,640 --> 00:02:50,640 Now the final one is the not operator and all that this does is it basically 40 00:02:51,160 --> 00:02:55,360 reverses a condition. So if the condition is false, 41 00:02:55,390 --> 00:02:58,900 then it becomes true. If it's true, then it becomes false. 42 00:02:59,830 --> 00:03:01,390 If I wrote not 43 00:03:01,570 --> 00:03:06,570 and then I wrote the condition A is greater than 15. A greater than 15 is 44 00:03:09,550 --> 00:03:14,410 definitely false, 12 is less than 15. But by putting the not there 45 00:03:14,410 --> 00:03:18,340 it's going to reverse this, so going from false to true. 46 00:03:18,580 --> 00:03:21,790 So when I hit enter, you'll see it is now true. 47 00:03:23,530 --> 00:03:25,480 Coming back to our rollercoaster ticketing, 48 00:03:25,720 --> 00:03:30,670 let's say that the rollercoaster company decided that for everybody who was 49 00:03:30,670 --> 00:03:34,600 having a midlife crisis, they would give them free tickets. 50 00:03:35,020 --> 00:03:36,790 And according to Wikipedia, 51 00:03:36,880 --> 00:03:41,880 midlife crises typically occur when you're a 45 to 55 years old. 52 00:03:42,760 --> 00:03:46,390 Let's see if we can incorporate this into our code. 53 00:03:46,960 --> 00:03:51,490 So let's say that in addition to these existing price categories, 54 00:03:51,700 --> 00:03:56,700 what if you had to add a separate price category for those people who are aged 55 00:03:57,190 --> 00:04:02,190 between 45 and 55 and those people get to ride for free? 56 00:04:03,700 --> 00:04:06,910 Do you think you would be able to change the code using what you've learned 57 00:04:06,940 --> 00:04:11,940 about logical operators in order to incorporate this addition to our program? 58 00:04:12,730 --> 00:04:14,260 Pause the video and give that a go. 59 00:04:17,970 --> 00:04:21,720 So we've currently got three conditions: age, 60 00:04:21,750 --> 00:04:26,750 less than 12, age between 12 and 18, and finally everybody else. 61 00:04:27,750 --> 00:04:31,770 Now instead of just finishing up there, 62 00:04:32,580 --> 00:04:34,770 let's go ahead and add another elif. 63 00:04:35,130 --> 00:04:37,740 And here we're going to combine two conditions. 64 00:04:38,250 --> 00:04:43,250 We're going to say if the age is greater than or equal to 45 and the age is less 65 00:04:47,790 --> 00:04:52,790 than or equal to 55, then we get to catch that midlife crisis window. 66 00:04:54,840 --> 00:04:55,080 Well, 67 00:04:55,080 --> 00:05:00,030 in this case, we're going to print something like-- we're going to say "Everything's 68 00:05:00,030 --> 00:05:02,520 going to be ok. Have a free ride on us!" 69 00:05:04,530 --> 00:05:05,190 And in fact, 70 00:05:05,190 --> 00:05:10,190 we don't need to modify the bill in any way because we know that with 71 00:05:11,820 --> 00:05:16,820 if, elif and else statements is that once this condition matches, 72 00:05:19,260 --> 00:05:22,350 then everything that's inside this block, 73 00:05:22,350 --> 00:05:26,850 so everything that's indented inside this elif is going to be carried out 74 00:05:26,910 --> 00:05:28,350 namely printing this out, 75 00:05:28,890 --> 00:05:33,890 and then it's going to skip the rest of this if/else block and continue on. 76 00:05:36,630 --> 00:05:37,890 Now, if they want to photo this, 77 00:05:37,890 --> 00:05:41,790 they'll have to pay $3 but at least their ticket is free. 78 00:05:42,150 --> 00:05:47,150 And we've been able to do this because we know about the and logical operator. 79 00:05:48,720 --> 00:05:49,920 In the next lesson, 80 00:05:49,980 --> 00:05:54,960 we're going to practice using logical operators and more by completing another 81 00:05:54,960 --> 00:05:58,380 code challenge. So for all of that and more, I'll see you there. 7792