1 1 00:00:00,500 --> 00:00:01,890 Hi guys and welcome back. 2 2 00:00:01,890 --> 00:00:05,100 Just a quick video to tell you about Booleans. 3 3 00:00:05,100 --> 00:00:09,680 A Boolean is a value that can be either true or false. 4 4 00:00:09,680 --> 00:00:11,830 And we can use that to make decisions, 5 5 00:00:11,830 --> 00:00:13,900 for example, using Boolean logic, 6 6 00:00:13,900 --> 00:00:17,690 we can tell whether a user's age is over 18. 7 7 00:00:17,690 --> 00:00:20,060 Or whether the user's character in a game 8 8 00:00:20,060 --> 00:00:21,910 has pressed the up arrow. 9 9 00:00:21,910 --> 00:00:24,430 Things like that are what we need Booleans for 10 10 00:00:24,430 --> 00:00:26,100 and they are everywhere in Python 11 11 00:00:26,100 --> 00:00:27,180 and in Programming. 12 12 00:00:27,180 --> 00:00:28,580 Let's learn more about them. 13 13 00:00:29,730 --> 00:00:32,900 Booleans are created by using comparisons. 14 14 00:00:32,900 --> 00:00:34,650 So, you can compare two things together 15 15 00:00:34,650 --> 00:00:36,410 to calculate whether two things 16 16 00:00:36,410 --> 00:00:38,580 are the same or different, 17 17 00:00:38,580 --> 00:00:42,450 for example, if you print five equal equal five, 18 18 00:00:42,450 --> 00:00:45,000 this is a Boolean comparison, 19 19 00:00:45,000 --> 00:00:47,030 five equal equal five. 20 20 00:00:47,030 --> 00:00:48,680 Notice that a single equal sign 21 21 00:00:48,680 --> 00:00:51,370 is used to assign a value to a variable. 22 22 00:00:51,370 --> 00:00:53,420 But two equal signs, one after another 23 23 00:00:53,420 --> 00:00:56,210 are used to compare two things. 24 24 00:00:56,210 --> 00:00:57,700 And what we're comparing here is, 25 25 00:00:57,700 --> 00:00:59,740 five and we're gonna check whether it is 26 26 00:00:59,740 --> 00:01:02,520 exactly equal to five. 27 27 00:01:02,520 --> 00:01:04,630 So, these two numbers here are being compared 28 28 00:01:04,630 --> 00:01:06,290 and we're going to get true, 29 29 00:01:06,290 --> 00:01:07,820 if they are exactly equal 30 30 00:01:07,820 --> 00:01:09,470 and we're going to get false if they are 31 31 00:01:09,470 --> 00:01:11,250 in any way different. 32 32 00:01:11,250 --> 00:01:13,170 So, if I run this here, you'll see 33 33 00:01:13,170 --> 00:01:15,013 that we get true out. 34 34 00:01:17,540 --> 00:01:19,030 As well as equal equal, 35 35 00:01:19,030 --> 00:01:22,010 you can use the typical maths operators 36 36 00:01:22,010 --> 00:01:23,310 such as greater than, 37 37 00:01:23,310 --> 00:01:25,640 to calculate whether a number is greater than 38 38 00:01:25,640 --> 00:01:26,503 another number. 39 39 00:01:27,780 --> 00:01:29,483 And there you get false. 40 40 00:01:32,090 --> 00:01:34,162 As a special case, you've also got, 41 41 00:01:34,162 --> 00:01:37,360 exclamation mark equal, which is used 42 42 00:01:37,360 --> 00:01:39,900 to tell whether two things are different. 43 43 00:01:39,900 --> 00:01:41,520 So, what this reads as is, 44 44 00:01:41,520 --> 00:01:44,490 is 10 different from 10? 45 45 00:01:44,490 --> 00:01:47,220 So, again, you'll get true if they are different 46 46 00:01:47,220 --> 00:01:49,683 and you'll get false if the are not different. 47 47 00:01:50,950 --> 00:01:54,000 So, here we should get false, 48 48 00:01:54,000 --> 00:01:55,723 because they are not different. 49 49 00:01:57,030 --> 00:01:58,770 Other comparisons that are available 50 50 00:01:58,770 --> 00:02:00,880 as well as equal equal, not equal 51 51 00:02:00,880 --> 00:02:03,900 and greater than are less than 52 52 00:02:03,900 --> 00:02:05,590 and greater than are equal to, 53 53 00:02:05,590 --> 00:02:06,900 or less than are equal to. 54 54 00:02:06,900 --> 00:02:08,970 And this is how you write them in Python. 55 55 00:02:08,970 --> 00:02:10,280 So, you can check whether something is 56 56 00:02:10,280 --> 00:02:12,850 less than one thing, whether it's greater than 57 57 00:02:12,850 --> 00:02:14,170 or equal to something else 58 58 00:02:14,170 --> 00:02:15,260 or whether it's less than 59 59 00:02:15,260 --> 00:02:16,773 or equal to something else. 60 60 00:02:18,160 --> 00:02:18,993 I'll say at this point, 61 61 00:02:18,993 --> 00:02:20,850 that you can use these operations, 62 62 00:02:20,850 --> 00:02:22,530 not only on numbers, 63 63 00:02:22,530 --> 00:02:24,650 but on any other value including lists, 64 64 00:02:24,650 --> 00:02:26,730 and tuples and strings and what not, 65 65 00:02:26,730 --> 00:02:28,720 but they can behave differently depending 66 66 00:02:28,720 --> 00:02:31,270 on what type of data you use them on. 67 67 00:02:31,270 --> 00:02:32,300 We're going to learn more 68 68 00:02:32,300 --> 00:02:34,690 and get more acquainted with how they behave 69 69 00:02:34,690 --> 00:02:36,830 in different scenarios, as we go along 70 70 00:02:36,830 --> 00:02:39,590 with better examples, of course. 71 71 00:02:39,590 --> 00:02:41,590 So, these are the comparisons 72 72 00:02:41,590 --> 00:02:43,810 and as well as comparisons, you've also got 73 73 00:02:43,810 --> 00:02:45,080 a few Python key words 74 74 00:02:45,080 --> 00:02:47,663 that you can use to calculate Booleans. 75 75 00:02:49,300 --> 00:02:52,320 One of the more confusing key words in Python, 76 76 00:02:52,320 --> 00:02:53,780 when you're talking about Booleans 77 77 00:02:53,780 --> 00:02:56,370 is the ease key word. 78 78 00:02:56,370 --> 00:02:58,160 So, here we've got two list, 79 79 00:02:58,160 --> 00:02:59,870 friends and abroad and they have 80 80 00:02:59,870 --> 00:03:02,270 the exact same elements inside them. 81 81 00:03:02,270 --> 00:03:05,860 You can print whether friends equal equal abroad 82 82 00:03:05,860 --> 00:03:07,630 and when you run this code, 83 83 00:03:07,630 --> 00:03:09,460 you get back true, 84 84 00:03:09,460 --> 00:03:11,850 because the equal equal sign, 85 85 00:03:11,850 --> 00:03:14,500 when you're talking about two different lists, 86 86 00:03:14,500 --> 00:03:16,470 compares whether the elements inside them 87 87 00:03:16,470 --> 00:03:17,780 are the same. 88 88 00:03:17,780 --> 00:03:20,300 And here, because you're comparing two strings, 89 89 00:03:20,300 --> 00:03:22,070 then Python can detect 90 90 00:03:22,070 --> 00:03:24,383 that these two lists are actually the same. 91 91 00:03:25,300 --> 00:03:27,850 However, a lot of new Python developers 92 92 00:03:27,850 --> 00:03:30,470 will try to do friends is abroad, 93 93 00:03:30,470 --> 00:03:32,590 which is something you can do in Python. 94 94 00:03:32,590 --> 00:03:34,670 But you won't get what you expect 95 95 00:03:34,670 --> 00:03:36,630 because you get false. 96 96 00:03:36,630 --> 00:03:39,210 That is because when you create a new list, 97 97 00:03:39,210 --> 00:03:41,630 Python goes and creates some space 98 98 00:03:41,630 --> 00:03:44,370 in its memory for this new list. 99 99 00:03:44,370 --> 00:03:46,660 The elements can be stored somewhere else, 100 100 00:03:46,660 --> 00:03:50,313 but the list itself has its own area in memory. 101 101 00:03:51,260 --> 00:03:53,580 Then when you create another list, 102 102 00:03:53,580 --> 00:03:56,080 it goes and creates another area in memory 103 103 00:03:56,080 --> 00:03:57,810 for this other list. 104 104 00:03:57,810 --> 00:04:01,130 The elements inside the list were created separately 105 105 00:04:01,130 --> 00:04:03,920 and they could be the same between both lists, 106 106 00:04:03,920 --> 00:04:07,210 but the lists themselves are different. 107 107 00:04:07,210 --> 00:04:10,450 And that is what the is keyword checks in Python. 108 108 00:04:10,450 --> 00:04:14,050 It checks whether two elements are exactly the same thing, 109 109 00:04:14,050 --> 00:04:16,870 not whether they have the same elements inside them 110 110 00:04:16,870 --> 00:04:19,000 or whether they are similar. 111 111 00:04:19,000 --> 00:04:21,180 So, again the is keyword is to compare 112 112 00:04:21,180 --> 00:04:23,800 whether two elements are the same thing. 113 113 00:04:23,800 --> 00:04:26,750 So, if you do friends is friends, for example, 114 114 00:04:26,750 --> 00:04:28,663 you're going to get true. 115 115 00:04:29,780 --> 00:04:33,040 If say abroad equal friends up here 116 116 00:04:33,040 --> 00:04:35,450 and then you check whether friends is abroad, 117 117 00:04:35,450 --> 00:04:37,280 you're also going to get true 118 118 00:04:37,280 --> 00:04:39,740 because you haven't created two lists. 119 119 00:04:39,740 --> 00:04:42,360 You've just pointed the two variables 120 120 00:04:42,360 --> 00:04:43,780 to the same list. 121 121 00:04:43,780 --> 00:04:46,490 And that again is what the is keyword is for, 122 122 00:04:46,490 --> 00:04:48,920 I recommend you almost never use it. 123 123 00:04:48,920 --> 00:04:50,680 You're almost always gonna want to use 124 124 00:04:50,680 --> 00:04:51,803 the double equal sign. 125 125 00:04:52,930 --> 00:04:54,660 All right, that's it for comparisons 126 126 00:04:54,660 --> 00:04:56,660 and this brief introduction to Booleans. 127 127 00:04:56,660 --> 00:04:58,550 Let's learn more in the next video. 128 128 00:04:58,550 --> 00:04:59,500 I'll see you there.