1 00:00:00,930 --> 00:00:02,220 -: Welcome back. 2 00:00:02,220 --> 00:00:05,460 So far we've learned a few built-in functions 3 00:00:05,460 --> 00:00:07,290 that Python has. 4 00:00:07,290 --> 00:00:09,450 Few built-in actions, right? 5 00:00:09,450 --> 00:00:11,520 Actions that we can take on data. 6 00:00:11,520 --> 00:00:13,800 And we learned about SDR. 7 00:00:13,800 --> 00:00:16,350 We learned about INT. 8 00:00:16,350 --> 00:00:18,480 We learned about Float 9 00:00:18,480 --> 00:00:20,730 and the Type conversion that we can do. 10 00:00:20,730 --> 00:00:22,920 We also learned about Type. 11 00:00:22,920 --> 00:00:23,753 We also learned 12 00:00:23,753 --> 00:00:28,680 about Print and these built in functions in Python. 13 00:00:28,680 --> 00:00:32,369 Well, there's a few of them and I'll link to this resource 14 00:00:32,369 --> 00:00:35,160 but there's not too, too many. 15 00:00:35,160 --> 00:00:37,080 As a matter of fact, we've also seen ones 16 00:00:37,080 --> 00:00:42,080 like ABS or Round in our Numbers video. 17 00:00:46,080 --> 00:00:51,080 So Numbers had some functions that we can use, 18 00:00:51,150 --> 00:00:52,383 some built-in functions. 19 00:00:53,836 --> 00:00:57,600 Well, Strings also has a very useful one called Len 20 00:00:57,600 --> 00:01:00,750 which stands for length. 21 00:01:00,750 --> 00:01:04,140 So as you guessed it, if I type 22 00:01:04,140 --> 00:01:05,310 in something like this 23 00:01:05,310 --> 00:01:09,870 and I print this out and I click run 24 00:01:09,870 --> 00:01:11,310 I get nine. 25 00:01:11,310 --> 00:01:13,440 Because it's calculating the length 26 00:01:13,440 --> 00:01:15,060 of the string in our case. 27 00:01:15,060 --> 00:01:20,060 1, 2, 3, 4, 5, 6, 7, 8, 9. 28 00:01:22,380 --> 00:01:25,980 The length of the string is nine. 29 00:01:25,980 --> 00:01:27,780 Now, you have to be careful here 30 00:01:27,780 --> 00:01:30,810 because the length itself doesn't start at zero 31 00:01:30,810 --> 00:01:32,490 as we've seen with indexes. 32 00:01:32,490 --> 00:01:35,940 Instead, it counts like humans do from one. 33 00:01:35,940 --> 00:01:40,653 So a neat thing to do here is I can do something like this. 34 00:01:42,000 --> 00:01:46,403 Let's say that we have a variable Greet that equals hello. 35 00:01:49,140 --> 00:01:53,193 Well, I can grab the Greet variable, 36 00:01:54,870 --> 00:01:55,830 which is a string 37 00:01:55,830 --> 00:02:00,830 and use string slicing to grab, well, the first 38 00:02:01,950 --> 00:02:04,530 and then go all the way until the end. 39 00:02:04,530 --> 00:02:06,690 Now, the default already does this. 40 00:02:06,690 --> 00:02:11,690 If I leave it like this, it's going to grab hello. 41 00:02:12,648 --> 00:02:14,396 Oh, and make sure I add a bracket here. 42 00:02:14,396 --> 00:02:15,229 Let's click run. 43 00:02:15,229 --> 00:02:16,062 I get hello. 44 00:02:17,400 --> 00:02:22,260 Now, if I do zero to length of greet 45 00:02:24,652 --> 00:02:25,860 What does that mean? 46 00:02:25,860 --> 00:02:30,360 Well, if I click run, I still get hello, because the length 47 00:02:30,360 --> 00:02:33,933 of Greet is nine. 48 00:02:37,020 --> 00:02:37,853 Like so. 49 00:02:38,963 --> 00:02:42,750 Now, this length function is quite useful 50 00:02:42,750 --> 00:02:45,300 and we're going to use it a lot in this course. 51 00:02:45,300 --> 00:02:48,000 But I want to introduce to you the concept of built-in 52 00:02:48,000 --> 00:02:53,000 functions as well as what we call built-in methods. 53 00:02:54,510 --> 00:02:56,373 Hmm, what does that mean? 54 00:02:58,407 --> 00:03:00,060 A built-in function had this syntax 55 00:03:00,060 --> 00:03:02,940 of the word that was highlighted in blue 56 00:03:02,940 --> 00:03:07,940 and then we used curly brackets to perform some action 57 00:03:08,460 --> 00:03:10,740 on a data type. 58 00:03:10,740 --> 00:03:14,340 However, Python also has this idea of methods. 59 00:03:14,340 --> 00:03:17,130 And methods are similar to functions, 60 00:03:17,130 --> 00:03:20,850 but they they are owned by something. 61 00:03:20,850 --> 00:03:25,680 So for example, in Python we have string methods. 62 00:03:25,680 --> 00:03:27,330 So these are methods 63 00:03:27,330 --> 00:03:31,710 or actions that only strings can perform. 64 00:03:31,710 --> 00:03:33,240 And don't worry, this is something 65 00:03:33,240 --> 00:03:34,680 that we'll talk more about 66 00:03:34,680 --> 00:03:37,860 when we talk about classes and functions. 67 00:03:37,860 --> 00:03:42,000 But for now, Python, for example, has string methods. 68 00:03:42,000 --> 00:03:43,560 So these are methods 69 00:03:43,560 --> 00:03:46,861 that we can use specifically for strings. 70 00:03:46,861 --> 00:03:49,300 And methods have a special syntax 71 00:03:50,324 --> 00:03:52,908 where instead of just the word with the curly brackets, 72 00:03:52,908 --> 00:03:55,803 it usually has a dot in front of it. 73 00:03:56,919 --> 00:03:59,400 So dot, and then some sort of word. 74 00:03:59,400 --> 00:04:02,490 And we've actually seen one format, right? 75 00:04:02,490 --> 00:04:07,490 Dot format, curly brackets or brackets is a method. 76 00:04:07,560 --> 00:04:11,190 And if I go to Python string methods and I scroll down 77 00:04:11,190 --> 00:04:13,890 or I scroll up, we see that format. 78 00:04:13,890 --> 00:04:17,523 Format specific values in a string is a method. 79 00:04:18,660 --> 00:04:20,910 Now, why do we care? 80 00:04:20,910 --> 00:04:25,910 Well, with this Python gives us automatic tools 81 00:04:26,040 --> 00:04:27,990 that we can use on strings. 82 00:04:27,990 --> 00:04:31,083 So let's explore some of these string methods. 83 00:04:32,310 --> 00:04:34,503 Let's create a quote here. 84 00:04:35,959 --> 00:04:38,853 And the quote is going to be to be or not to be. 85 00:04:40,920 --> 00:04:43,233 Now in here with this quote, 86 00:04:44,314 --> 00:04:47,430 we can use some methods on this string. 87 00:04:47,430 --> 00:04:49,540 Now, I'm not gonna go through everything 88 00:04:50,490 --> 00:04:52,620 because, well, 60% of these you're most 89 00:04:52,620 --> 00:04:55,440 likely never going to use in your career. 90 00:04:55,440 --> 00:04:57,570 I'm gonna go over the important ones that you'll see 91 00:04:57,570 --> 00:05:00,000 over and over again, but I'll also link to this 92 00:05:00,000 --> 00:05:02,520 so that you can see this for yourself as a reference. 93 00:05:02,520 --> 00:05:06,010 Remember, as a programmer your job is not to memorize this 94 00:05:07,051 --> 00:05:09,420 and read a language like you read a dictionary. 95 00:05:09,420 --> 00:05:12,930 Instead it is to know that this resource exists 96 00:05:12,930 --> 00:05:15,270 and it's for you to explore 97 00:05:15,270 --> 00:05:18,870 and learn as a specific problem occurs. 98 00:05:18,870 --> 00:05:21,033 But let's get back to the task at hand. 99 00:05:22,650 --> 00:05:27,197 One thing that we can do is to use the upper method. 100 00:05:28,620 --> 00:05:31,332 We use a dot and then type in upper 101 00:05:31,332 --> 00:05:34,200 and then the curly brackets. 102 00:05:34,200 --> 00:05:37,950 And luckily for us, our editor shows us 103 00:05:37,950 --> 00:05:39,840 that this actually exists 104 00:05:39,840 --> 00:05:41,610 because of the dropdown menu. 105 00:05:41,610 --> 00:05:43,350 So what happens now? 106 00:05:43,350 --> 00:05:44,943 If I print this, 107 00:05:46,119 --> 00:05:48,393 and I click run, 108 00:05:50,130 --> 00:05:50,963 look at that. 109 00:05:50,963 --> 00:05:53,040 Everything gets capitalized. 110 00:05:53,040 --> 00:05:54,513 To be or not to be. 111 00:05:56,520 --> 00:06:01,520 There is also another one we can use called Capitalize. 112 00:06:02,910 --> 00:06:05,640 What's the difference between the two? 113 00:06:05,640 --> 00:06:08,250 Well, if I run, you see 114 00:06:08,250 --> 00:06:12,063 that it capitalizes the beginning of the sentence. 115 00:06:13,470 --> 00:06:16,050 And by the way, your editor, or in our case, our repl 116 00:06:16,050 --> 00:06:17,610 if you hover over this 117 00:06:17,610 --> 00:06:20,643 it'll actually tell you what it does. 118 00:06:21,780 --> 00:06:24,933 It returns a capitalized version of S. 119 00:06:26,280 --> 00:06:27,990 So whatever is to the left 120 00:06:27,990 --> 00:06:28,823 of the dot. 121 00:06:30,150 --> 00:06:32,910 And a good editor will actually 122 00:06:32,910 --> 00:06:35,640 show you all the things available to you. 123 00:06:35,640 --> 00:06:39,000 So as soon as you press a dot, look at that. 124 00:06:39,000 --> 00:06:41,670 I see all these purple boxes 125 00:06:41,670 --> 00:06:45,990 which are methods that are available to me for a string. 126 00:06:45,990 --> 00:06:48,660 And you see there's a lot of them. 127 00:06:48,660 --> 00:06:49,650 Now, don't worry 128 00:06:49,650 --> 00:06:53,010 about these double underscores, these dunder methods. 129 00:06:53,010 --> 00:06:55,080 Because this is something that we'll talk 130 00:06:55,080 --> 00:06:56,910 about when we talk about classes. 131 00:06:56,910 --> 00:06:58,328 But you can see 132 00:06:58,328 --> 00:07:01,170 that you have different things that you can use. 133 00:07:01,170 --> 00:07:03,362 For example, you have lower instead of upper 134 00:07:03,362 --> 00:07:05,763 it lower cases everything. 135 00:07:07,860 --> 00:07:09,990 What if I want to use find? 136 00:07:09,990 --> 00:07:13,288 For example, and find simply says 137 00:07:13,288 --> 00:07:18,288 hey, does B exist in the code to be or not to be? 138 00:07:19,113 --> 00:07:24,113 And if I click run, well, it tells me that yes. 139 00:07:25,680 --> 00:07:30,633 Quote dot find has a B, and it starts at index of 3. 140 00:07:31,650 --> 00:07:36,650 So if I go to 0, 1, 2, and then look at that 3. 141 00:07:37,170 --> 00:07:41,490 So we have find, which finds us the first occurrence 142 00:07:41,490 --> 00:07:43,683 of a piece of text. 143 00:07:45,150 --> 00:07:49,410 You also have things like Replace, where I can replace 144 00:07:49,410 --> 00:07:54,270 whatever I give it as the first thing, and then separate it 145 00:07:54,270 --> 00:07:55,443 to the second thing. 146 00:07:56,451 --> 00:08:00,210 So you can see over here it tells me old and then comma new. 147 00:08:00,210 --> 00:08:03,390 And I can replace this with me. 148 00:08:03,390 --> 00:08:05,090 If I click run, 149 00:08:05,090 --> 00:08:08,220 I get to me or not to me. 150 00:08:08,220 --> 00:08:12,390 So this replaces all the occurrences of be. 151 00:08:12,390 --> 00:08:16,710 Now, the final thing I wanna point out to you is that 152 00:08:16,710 --> 00:08:19,473 if I print here, quote, 153 00:08:20,790 --> 00:08:23,250 what do you think is going to happen? 154 00:08:23,250 --> 00:08:28,230 I've printed here and I replaced to me, to be 155 00:08:28,230 --> 00:08:30,700 or not to be with to me or not to me 156 00:08:32,620 --> 00:08:34,049 quite a selfish quote. 157 00:08:34,049 --> 00:08:36,960 But if I print this again on the fifth line 158 00:08:36,960 --> 00:08:38,789 what do you think will happen? 159 00:08:38,789 --> 00:08:39,623 Let's find out. 160 00:08:41,700 --> 00:08:42,533 Whoa. 161 00:08:43,799 --> 00:08:45,483 Is this what you expected? 162 00:08:46,440 --> 00:08:48,510 Think about why this might happen based 163 00:08:48,510 --> 00:08:49,743 on what we've learned. 164 00:08:51,180 --> 00:08:52,013 Here's the thing. 165 00:08:52,013 --> 00:08:54,810 Remember, strings are immutable 166 00:08:54,810 --> 00:08:57,120 That is, they cannot be changed. 167 00:08:57,120 --> 00:09:01,500 We can override them if we want, but we don't change them. 168 00:09:01,500 --> 00:09:03,660 We either create them or destroy them. 169 00:09:03,660 --> 00:09:06,480 In our case, when we do quote 170 00:09:06,480 --> 00:09:09,097 dot replace to me or not to me, 171 00:09:09,097 --> 00:09:12,183 it's creating a new string. 172 00:09:13,080 --> 00:09:16,590 Now, we're not assigning this string to anything. 173 00:09:16,590 --> 00:09:20,640 So eventually after we print it, we remove it from memory. 174 00:09:20,640 --> 00:09:25,020 But if I do something like this 175 00:09:25,020 --> 00:09:27,630 where I have quote 176 00:09:27,630 --> 00:09:32,630 two equals quote, dot replace and I print quote two. 177 00:09:37,157 --> 00:09:40,832 Well in our case, we're creating a whole new string. 178 00:09:40,832 --> 00:09:41,665 We're creating a string. 179 00:09:41,665 --> 00:09:44,250 But we never modify the original string 180 00:09:44,250 --> 00:09:46,200 because it's immutable. 181 00:09:46,200 --> 00:09:51,200 So that quote always stays the way it is. 182 00:09:51,300 --> 00:09:52,500 Until we destroy it. 183 00:09:52,500 --> 00:09:55,410 Until we remove it, our program ends. 184 00:09:55,410 --> 00:09:57,153 This is going to exist. 185 00:09:58,230 --> 00:10:00,630 All right, hope you're having fun. 186 00:10:00,630 --> 00:10:03,363 Hang in there more to learn in the next video.