1 1 00:00:00,400 --> 00:00:02,100 Hi, guys, and welcome back. 2 2 00:00:02,100 --> 00:00:03,320 In this video, we're going to learn 3 3 00:00:03,320 --> 00:00:05,980 about the in keyword in Python. 4 4 00:00:05,980 --> 00:00:07,920 The in keyword is something we can use 5 5 00:00:07,920 --> 00:00:09,750 to check for membership, 6 6 00:00:09,750 --> 00:00:12,580 whether one thing is inside a list 7 7 00:00:12,580 --> 00:00:14,123 or a tuple or a set. 8 8 00:00:14,960 --> 00:00:16,370 Let's get started. 9 9 00:00:16,370 --> 00:00:17,930 I'll have a list of friends, 10 10 00:00:17,930 --> 00:00:22,440 which contains Rolf, Bob, and Jen. 11 11 00:00:22,440 --> 00:00:24,100 And then we can very easily print 12 12 00:00:24,100 --> 00:00:27,423 whether Jen is in friends. 13 13 00:00:28,310 --> 00:00:31,300 And this is going to check whether the string Jen 14 14 00:00:31,300 --> 00:00:35,180 is one of the members in this list. 15 15 00:00:35,180 --> 00:00:37,690 So if we save that and run it, 16 16 00:00:37,690 --> 00:00:39,623 you'll see that we get back true. 17 17 00:00:41,950 --> 00:00:44,160 Now let's say that we have a set 18 18 00:00:44,160 --> 00:00:46,470 of the movies we've recently watched. 19 19 00:00:46,470 --> 00:00:47,650 I'm using a set here 20 20 00:00:47,650 --> 00:00:51,800 because movies are unique, so you can't have duplicates 21 21 00:00:51,800 --> 00:00:55,470 and having a set actually helps you prevent duplication. 22 22 00:00:55,470 --> 00:00:57,270 In addition, the movies that we've watched 23 23 00:00:57,270 --> 00:00:59,890 in this case don't have any specific order. 24 24 00:00:59,890 --> 00:01:01,650 So we don't care about the order, 25 25 00:01:01,650 --> 00:01:04,030 and therefore a set is a perfect structure 26 26 00:01:04,030 --> 00:01:05,503 to put these movies into. 27 27 00:01:06,360 --> 00:01:08,550 Then we are going to ask the user 28 28 00:01:08,550 --> 00:01:10,493 for a movie they've watched recently. 29 29 00:01:15,420 --> 00:01:16,900 And finally, we're going to print 30 30 00:01:16,900 --> 00:01:20,633 whether that movie is in our movies watched. 31 31 00:01:22,200 --> 00:01:23,310 If we run this, 32 32 00:01:23,310 --> 00:01:27,430 then you'll see that if we type The Matrix, you get true, 33 33 00:01:27,430 --> 00:01:29,920 but if you type Monty Python, 34 34 00:01:29,920 --> 00:01:31,593 then you'll get false. 35 35 00:01:33,010 --> 00:01:35,810 The in keyword works in sequences 36 36 00:01:35,810 --> 00:01:38,050 like lists, tuples, sets. 37 37 00:01:38,050 --> 00:01:39,780 It also works in strings, actually, 38 38 00:01:39,780 --> 00:01:42,200 so you can check whether a string 39 39 00:01:42,200 --> 00:01:45,350 is inside another string, such as a substring. 40 40 00:01:45,350 --> 00:01:50,290 For example, R-I-X would be in The Matrix. 41 41 00:01:50,290 --> 00:01:53,060 So you can do checks like that, as well, if you want. 42 42 00:01:53,060 --> 00:01:54,220 Let's move on to the next video 43 43 00:01:54,220 --> 00:01:56,440 where we're gonna learn how to use if statements 44 44 00:01:56,440 --> 00:01:58,030 with this syntax here 45 45 00:01:58,030 --> 00:02:00,610 so that we can create even more powerful programmes. 46 46 00:02:00,610 --> 00:02:01,560 I'll see you there.