WEBVTT 1 00:00:00.500 --> 00:00:01.890 Hi guys and welcome back. 2 00:00:01.890 --> 00:00:05.100 Just a quick video to tell you about Booleans. 3 00:00:05.100 --> 00:00:09.680 A Boolean is a value that can be either true or false. 4 00:00:09.680 --> 00:00:11.830 And we can use that to make decisions, 5 00:00:11.830 --> 00:00:13.900 for example, using Boolean logic, 6 00:00:13.900 --> 00:00:17.690 we can tell whether a user's age is over 18. 7 00:00:17.690 --> 00:00:20.060 Or whether the user's character in a game 8 00:00:20.060 --> 00:00:21.910 has pressed the up arrow. 9 00:00:21.910 --> 00:00:24.430 Things like that are what we need Booleans for 10 00:00:24.430 --> 00:00:26.100 and they are everywhere in Python 11 00:00:26.100 --> 00:00:27.180 and in Programming. 12 00:00:27.180 --> 00:00:28.580 Let's learn more about them. 13 00:00:29.730 --> 00:00:32.900 Booleans are created by using comparisons. 14 00:00:32.900 --> 00:00:34.650 So, you can compare two things together 15 00:00:34.650 --> 00:00:36.410 to calculate whether two things 16 00:00:36.410 --> 00:00:38.580 are the same or different, 17 00:00:38.580 --> 00:00:42.450 for example, if you print five equal equal five, 18 00:00:42.450 --> 00:00:45.000 this is a Boolean comparison, 19 00:00:45.000 --> 00:00:47.030 five equal equal five. 20 00:00:47.030 --> 00:00:48.680 Notice that a single equal sign 21 00:00:48.680 --> 00:00:51.370 is used to assign a value to a variable. 22 00:00:51.370 --> 00:00:53.420 But two equal signs, one after another 23 00:00:53.420 --> 00:00:56.210 are used to compare two things. 24 00:00:56.210 --> 00:00:57.700 And what we're comparing here is, 25 00:00:57.700 --> 00:00:59.740 five and we're gonna check whether it is 26 00:00:59.740 --> 00:01:02.520 exactly equal to five. 27 00:01:02.520 --> 00:01:04.630 So, these two numbers here are being compared 28 00:01:04.630 --> 00:01:06.290 and we're going to get true, 29 00:01:06.290 --> 00:01:07.820 if they are exactly equal 30 00:01:07.820 --> 00:01:09.470 and we're going to get false if they are 31 00:01:09.470 --> 00:01:11.250 in any way different. 32 00:01:11.250 --> 00:01:13.170 So, if I run this here, you'll see 33 00:01:13.170 --> 00:01:15.013 that we get true out. 34 00:01:17.540 --> 00:01:19.030 As well as equal equal, 35 00:01:19.030 --> 00:01:22.010 you can use the typical maths operators 36 00:01:22.010 --> 00:01:23.310 such as greater than, 37 00:01:23.310 --> 00:01:25.640 to calculate whether a number is greater than 38 00:01:25.640 --> 00:01:26.503 another number. 39 00:01:27.780 --> 00:01:29.483 And there you get false. 40 00:01:32.090 --> 00:01:34.162 As a special case, you've also got, 41 00:01:34.162 --> 00:01:37.360 exclamation mark equal, which is used 42 00:01:37.360 --> 00:01:39.900 to tell whether two things are different. 43 00:01:39.900 --> 00:01:41.520 So, what this reads as is, 44 00:01:41.520 --> 00:01:44.490 is 10 different from 10? 45 00:01:44.490 --> 00:01:47.220 So, again, you'll get true if they are different 46 00:01:47.220 --> 00:01:49.683 and you'll get false if the are not different. 47 00:01:50.950 --> 00:01:54.000 So, here we should get false, 48 00:01:54.000 --> 00:01:55.723 because they are not different. 49 00:01:57.030 --> 00:01:58.770 Other comparisons that are available 50 00:01:58.770 --> 00:02:00.880 as well as equal equal, not equal 51 00:02:00.880 --> 00:02:03.900 and greater than are less than 52 00:02:03.900 --> 00:02:05.590 and greater than are equal to, 53 00:02:05.590 --> 00:02:06.900 or less than are equal to. 54 00:02:06.900 --> 00:02:08.970 And this is how you write them in Python. 55 00:02:08.970 --> 00:02:10.280 So, you can check whether something is 56 00:02:10.280 --> 00:02:12.850 less than one thing, whether it's greater than 57 00:02:12.850 --> 00:02:14.170 or equal to something else 58 00:02:14.170 --> 00:02:15.260 or whether it's less than 59 00:02:15.260 --> 00:02:16.773 or equal to something else. 60 00:02:18.160 --> 00:02:18.993 I'll say at this point, 61 00:02:18.993 --> 00:02:20.850 that you can use these operations, 62 00:02:20.850 --> 00:02:22.530 not only on numbers, 63 00:02:22.530 --> 00:02:24.650 but on any other value including lists, 64 00:02:24.650 --> 00:02:26.730 and tuples and strings and what not, 65 00:02:26.730 --> 00:02:28.720 but they can behave differently depending 66 00:02:28.720 --> 00:02:31.270 on what type of data you use them on. 67 00:02:31.270 --> 00:02:32.300 We're going to learn more 68 00:02:32.300 --> 00:02:34.690 and get more acquainted with how they behave 69 00:02:34.690 --> 00:02:36.830 in different scenarios, as we go along 70 00:02:36.830 --> 00:02:39.590 with better examples, of course. 71 00:02:39.590 --> 00:02:41.590 So, these are the comparisons 72 00:02:41.590 --> 00:02:43.810 and as well as comparisons, you've also got 73 00:02:43.810 --> 00:02:45.080 a few Python key words 74 00:02:45.080 --> 00:02:47.663 that you can use to calculate Booleans. 75 00:02:49.300 --> 00:02:52.320 One of the more confusing key words in Python, 76 00:02:52.320 --> 00:02:53.780 when you're talking about Booleans 77 00:02:53.780 --> 00:02:56.370 is the ease key word. 78 00:02:56.370 --> 00:02:58.160 So, here we've got two list, 79 00:02:58.160 --> 00:02:59.870 friends and abroad and they have 80 00:02:59.870 --> 00:03:02.270 the exact same elements inside them. 81 00:03:02.270 --> 00:03:05.860 You can print whether friends equal equal abroad 82 00:03:05.860 --> 00:03:07.630 and when you run this code, 83 00:03:07.630 --> 00:03:09.460 you get back true, 84 00:03:09.460 --> 00:03:11.850 because the equal equal sign, 85 00:03:11.850 --> 00:03:14.500 when you're talking about two different lists, 86 00:03:14.500 --> 00:03:16.470 compares whether the elements inside them 87 00:03:16.470 --> 00:03:17.780 are the same. 88 00:03:17.780 --> 00:03:20.300 And here, because you're comparing two strings, 89 00:03:20.300 --> 00:03:22.070 then Python can detect 90 00:03:22.070 --> 00:03:24.383 that these two lists are actually the same. 91 00:03:25.300 --> 00:03:27.850 However, a lot of new Python developers 92 00:03:27.850 --> 00:03:30.470 will try to do friends is abroad, 93 00:03:30.470 --> 00:03:32.590 which is something you can do in Python. 94 00:03:32.590 --> 00:03:34.670 But you won't get what you expect 95 00:03:34.670 --> 00:03:36.630 because you get false. 96 00:03:36.630 --> 00:03:39.210 That is because when you create a new list, 97 00:03:39.210 --> 00:03:41.630 Python goes and creates some space 98 00:03:41.630 --> 00:03:44.370 in its memory for this new list. 99 00:03:44.370 --> 00:03:46.660 The elements can be stored somewhere else, 100 00:03:46.660 --> 00:03:50.313 but the list itself has its own area in memory. 101 00:03:51.260 --> 00:03:53.580 Then when you create another list, 102 00:03:53.580 --> 00:03:56.080 it goes and creates another area in memory 103 00:03:56.080 --> 00:03:57.810 for this other list. 104 00:03:57.810 --> 00:04:01.130 The elements inside the list were created separately 105 00:04:01.130 --> 00:04:03.920 and they could be the same between both lists, 106 00:04:03.920 --> 00:04:07.210 but the lists themselves are different. 107 00:04:07.210 --> 00:04:10.450 And that is what the is keyword checks in Python. 108 00:04:10.450 --> 00:04:14.050 It checks whether two elements are exactly the same thing, 109 00:04:14.050 --> 00:04:16.870 not whether they have the same elements inside them 110 00:04:16.870 --> 00:04:19.000 or whether they are similar. 111 00:04:19.000 --> 00:04:21.180 So, again the is keyword is to compare 112 00:04:21.180 --> 00:04:23.800 whether two elements are the same thing. 113 00:04:23.800 --> 00:04:26.750 So, if you do friends is friends, for example, 114 00:04:26.750 --> 00:04:28.663 you're going to get true. 115 00:04:29.780 --> 00:04:33.040 If say abroad equal friends up here 116 00:04:33.040 --> 00:04:35.450 and then you check whether friends is abroad, 117 00:04:35.450 --> 00:04:37.280 you're also going to get true 118 00:04:37.280 --> 00:04:39.740 because you haven't created two lists. 119 00:04:39.740 --> 00:04:42.360 You've just pointed the two variables 120 00:04:42.360 --> 00:04:43.780 to the same list. 121 00:04:43.780 --> 00:04:46.490 And that again is what the is keyword is for, 122 00:04:46.490 --> 00:04:48.920 I recommend you almost never use it. 123 00:04:48.920 --> 00:04:50.680 You're almost always gonna want to use 124 00:04:50.680 --> 00:04:51.803 the double equal sign. 125 00:04:52.930 --> 00:04:54.660 All right, that's it for comparisons 126 00:04:54.660 --> 00:04:56.660 and this brief introduction to Booleans. 127 00:04:56.660 --> 00:04:58.550 Let's learn more in the next video. 128 00:04:58.550 --> 00:04:59.500 I'll see you there.