Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,070 --> 00:00:05,070 Yesterday you saw that we could use the Len function to get the number of 2 00:00:05,410 --> 00:00:09,640 characters in a string. So for example, when I write Len, 3 00:00:09,670 --> 00:00:12,580 hello and I print this out, 4 00:00:13,360 --> 00:00:17,500 we end up with 5. There's 5 characters in the string hello. 5 00:00:18,280 --> 00:00:19,570 Now here's a question. 6 00:00:20,170 --> 00:00:25,170 What happens if instead of counting the number of characters in a string, 7 00:00:26,200 --> 00:00:31,200 what if I put in a number instead and I wanted to know how many digits are in 8 00:00:31,780 --> 00:00:35,800 this number? Now if I go ahead and run this code, 9 00:00:35,980 --> 00:00:37,810 you'll see that it actually crashes. 10 00:00:38,260 --> 00:00:43,260 I get a whole bunch of red text and it tells me that there is a type error and 11 00:00:44,380 --> 00:00:49,150 something about the type int. So what is all of this about? 12 00:00:49,840 --> 00:00:54,370 Well, in order to understand it, we first have to learn about data types. 13 00:00:55,120 --> 00:00:59,680 Now on day 1, we already explored this data type called strings. 14 00:01:00,100 --> 00:01:03,760 Now you're probably not going to be surprised to learn that there's a whole lot 15 00:01:03,760 --> 00:01:05,770 more other data types out there. 16 00:01:06,250 --> 00:01:11,140 And today we're going to explore some of the most important and some of the most 17 00:01:11,140 --> 00:01:15,820 basic data types such as strings, integers, float, and booleans. 18 00:01:16,270 --> 00:01:18,580 And we'll explore each of these in detail. 19 00:01:19,300 --> 00:01:24,300 So go ahead and get hold of the day 2 start coding sandbox and go ahead and 20 00:01:25,540 --> 00:01:29,050 fork your own copy of it. Now once you've done that, 21 00:01:29,110 --> 00:01:31,360 let's take a look at some of the data types. 22 00:01:31,480 --> 00:01:34,240 So we already learned about strings, right? 23 00:01:34,360 --> 00:01:38,650 And we know that this is just a string of characters. 24 00:01:38,980 --> 00:01:43,980 So the word hello is comprised of these five characters strung together. 25 00:01:44,320 --> 00:01:47,680 And we always know that strings, when we create them, 26 00:01:47,890 --> 00:01:49,960 we have to create them with these double quotes around. 27 00:01:50,440 --> 00:01:53,110 Now because this is a string of characters, 28 00:01:53,470 --> 00:01:58,390 we can actually pull out each character individually. So we could, for example, 29 00:01:58,570 --> 00:02:02,890 instead of just writing hello, we can add some square brackets. 30 00:02:03,280 --> 00:02:06,220 So take a look on your keyboard and see where those are. 31 00:02:06,730 --> 00:02:11,730 And inside the square brackets, we can put the index or the position of the 32 00:02:12,730 --> 00:02:15,010 character that we want. So, for example, 33 00:02:15,010 --> 00:02:19,390 if I wanted to have the first character out of this word hello, 34 00:02:19,420 --> 00:02:21,310 I would put zero right here. 35 00:02:21,910 --> 00:02:26,350 And if I go ahead and print what this actually will give me, 36 00:02:26,800 --> 00:02:31,800 you'll see that you get capital H because that is the first character of this 37 00:02:32,890 --> 00:02:33,723 string. 38 00:02:33,970 --> 00:02:38,140 And it's really important to remember that programmers always start counting 39 00:02:38,140 --> 00:02:42,190 from zero because we work with binary, zeros and ones. 40 00:02:42,460 --> 00:02:46,810 So whenever you want to get hold of the first character or the first of 41 00:02:46,810 --> 00:02:49,480 anything, it always is at zero. 42 00:02:50,080 --> 00:02:54,910 So this method of pulling out a particular element from a string is called sub- 43 00:02:54,910 --> 00:02:58,960 scripting. And the number in between the square brackets determines 44 00:02:59,770 --> 00:03:01,270 which character you're going to pull out, 45 00:03:01,600 --> 00:03:06,600 and it just goes up from zero to one to two and so on and so forth. 46 00:03:07,240 --> 00:03:10,240 So whenever you get a result that's just off by one, 47 00:03:10,480 --> 00:03:15,480 then remember to check whether if you've started counting from zero or if you 48 00:03:15,580 --> 00:03:17,140 started counting from one. 49 00:03:18,040 --> 00:03:22,360 Now you can of course extend this and get hold of the last character. 50 00:03:22,570 --> 00:03:27,100 So pause the video and see if you can change the code so that 'o' gets printed 51 00:03:27,100 --> 00:03:29,440 out here. All right, 52 00:03:29,440 --> 00:03:33,760 so this is a simple as simply counting from zero, one, two, three, 53 00:03:33,940 --> 00:03:38,020 four. So if we change this to four and we run our code, 54 00:03:38,320 --> 00:03:41,080 then you'll see that 'o' gets printed instead of the H. 55 00:03:41,620 --> 00:03:44,980 So by using these square brackets and putting a number inside, 56 00:03:45,280 --> 00:03:50,280 we're able to dissect our string and pull out individual characters as and when 57 00:03:50,980 --> 00:03:51,813 we need it. 58 00:03:52,120 --> 00:03:55,840 And this will come in really handy in a lot of the programs that you'll write in 59 00:03:55,840 --> 00:03:56,673 the future. 60 00:03:57,220 --> 00:04:02,140 Now it's important to remember though that just because I can write a number 61 00:04:02,170 --> 00:04:03,520 like "123", 62 00:04:04,180 --> 00:04:07,660 as long as it's kept inside these double quotes, 63 00:04:07,990 --> 00:04:11,440 then this is not treated as a number by the computer. 64 00:04:11,440 --> 00:04:16,420 It's treated just as any other piece of text. You can't, for example, say, 65 00:04:16,480 --> 00:04:21,040 um, what is "123" + "345". 66 00:04:21,490 --> 00:04:25,720 If I try to print this, what do you think will happen? 67 00:04:26,260 --> 00:04:29,110 Do you think it will give me 123 + 345 68 00:04:29,110 --> 00:04:30,820 in the traditional sense, 69 00:04:30,820 --> 00:04:35,410 like calculating it or do you think it'll do something else? All right, 70 00:04:35,470 --> 00:04:39,970 let's hit run and we get 123345. 71 00:04:40,240 --> 00:04:44,140 So it's basically just concatenated these two strings together, 72 00:04:44,380 --> 00:04:49,330 just as we have done with other strings like hello and world, right? 73 00:04:50,170 --> 00:04:54,700 Because it sees the datatype of these two pieces of data as strings. 74 00:04:55,060 --> 00:04:56,650 When we use the plus sign, 75 00:04:56,830 --> 00:05:01,450 it will actually just concatenate these two things instead of doing a 76 00:05:01,450 --> 00:05:05,140 mathematical operation. Now if we want to do that, 77 00:05:05,200 --> 00:05:10,120 then we actually have to declare our number as a number data type. 78 00:05:10,450 --> 00:05:13,780 So one of the most common that you'll see is called an integer. 79 00:05:14,200 --> 00:05:18,250 So this is programming lingo for just whole numbers, numbers 80 00:05:18,250 --> 00:05:20,290 without any decimal places. 81 00:05:20,860 --> 00:05:25,000 And in order to create an integer or declare an integer data type, 82 00:05:25,300 --> 00:05:29,560 all you have to do is just write the number without anything else. 83 00:05:30,220 --> 00:05:34,300 So now if I just write the numbers, 123 + 345 84 00:05:34,300 --> 00:05:37,150 and then I go ahead and print this, 85 00:05:37,720 --> 00:05:40,720 then you'll see that we actually get 468. 86 00:05:40,720 --> 00:05:45,550 So it's actually being calculated because I've got actual numbers instead of 87 00:05:45,670 --> 00:05:46,540 strings. 88 00:05:47,290 --> 00:05:50,800 Just as we have some useful things that we can do with strings. 89 00:05:51,130 --> 00:05:53,650 There's some really handy things that you can do with integers. 90 00:05:54,400 --> 00:05:57,890 Commonly when we write large numbers, 91 00:05:58,100 --> 00:06:02,600 at least in the UK or in the US, we'd like to put commas in between the 92 00:06:02,600 --> 00:06:03,380 thousands. 93 00:06:03,380 --> 00:06:08,380 So when we think of large numbers with these commas in between to split it into 94 00:06:08,390 --> 00:06:11,720 an easier to understand number. In Python, 95 00:06:11,750 --> 00:06:16,750 we can replace those commas simply with underscores and it will be interpreted 96 00:06:16,820 --> 00:06:20,330 by the computer as if you had written this. 97 00:06:20,630 --> 00:06:23,960 So the computer actually removes those underscores and ignores it. 98 00:06:24,440 --> 00:06:29,120 The benefit is just for us humans to be able to visualize it more easily. 99 00:06:29,780 --> 00:06:32,060 So I mentioned that all whole numbers 100 00:06:32,060 --> 00:06:36,170 no matter if they're positive or negative, are called integers in programming. 101 00:06:36,770 --> 00:06:40,250 So what do you call it when you actually have decimal places? Well, 102 00:06:40,280 --> 00:06:45,280 they are called a float and this is short for a floating-point number. 103 00:06:45,680 --> 00:06:49,940 So for example, if you had um, the numbers of PI, 104 00:06:49,970 --> 00:06:51,770 you have 3.14159 105 00:06:51,830 --> 00:06:56,830 and this, because it has a decimal place, is now a float data type. 106 00:06:58,580 --> 00:07:03,580 So if you think of the decimal point as being able to float around the number 107 00:07:04,070 --> 00:07:06,020 because it could occur at any point, 108 00:07:06,290 --> 00:07:08,900 then you've got yourself a floating point number. 109 00:07:10,100 --> 00:07:14,090 Now the final data type is something called a boolean. 110 00:07:14,960 --> 00:07:18,740 And this is very simple. It only has two possible values, 111 00:07:19,100 --> 00:07:20,990 true or false. 112 00:07:21,350 --> 00:07:26,350 Now note how these values always begin with a capital T or capital F and they 113 00:07:27,410 --> 00:07:30,290 don't have any quotation marks around them or anything. 114 00:07:30,560 --> 00:07:35,510 So this is actually a data type which is going to be used a lot in your programs 115 00:07:35,780 --> 00:07:37,280 to test if something is true, 116 00:07:37,280 --> 00:07:41,300 if something is false and for your program to respond accordingly. 117 00:07:41,690 --> 00:07:44,390 So we're going to be using this a lot more in the future. 118 00:07:44,870 --> 00:07:49,250 Now that you've seen a lot of the basic data types, strings, integers, floats, 119 00:07:49,250 --> 00:07:50,083 and boolean, 120 00:07:50,270 --> 00:07:54,620 I want you to head over to the next lesson where I've got a quiz for you to see 121 00:07:54,620 --> 00:07:58,640 if you've made this knowledge your own. So head over to the quiz and give it a go. 11838