WEBVTT 0 00:00.260 --> 00:06.470 Now that we've learned all about loops in Python, we're finally ready to tackle our final project of 1 00:06.470 --> 00:09.890 the day, which is the PyPassword Generator. 2 00:10.160 --> 00:14.060 Our program will ask us, "How many letters would you like in your password?" 3 00:14.060 --> 00:16.640 So I will say I would like a long password. 4 00:16.640 --> 00:17.900 Let's say 14. 5 00:18.020 --> 00:19.400 "How many symbols?" 6 00:19.940 --> 00:20.570 3. 7 00:20.600 --> 00:21.740 "How many numbers?" 8 00:21.740 --> 00:22.550 4. 9 00:22.610 --> 00:29.370 And it's going to generate me a password that is almost completely impossible to crack by any hacker, 10 00:29.370 --> 00:31.140 no matter how talented they are. 11 00:31.320 --> 00:35.790 So the project of today is to build this password generator. 12 00:36.150 --> 00:42.600 Then you'll see that here, I've already included for you a list of all the letters in the alphabet, from 13 00:42.600 --> 00:46.290 A to Z, including the uppercase and lowercase letters. 14 00:46.350 --> 00:52.920 I've got a bunch of numbers and a bunch of symbols that are usually accepted by websites in the passwords. 15 00:53.350 --> 00:56.710 Now there's two levels to this project. 16 00:56.710 --> 01:04.930 You can either go for the Easy Version, where all you have to do is generate your password in sequence. 17 01:04.930 --> 01:10.930 So for example, if the user wanted four letters, two symbols and two numbers, then it might just 18 01:10.930 --> 01:18.290 look like this four letters and then two symbols and then two numbers. 19 01:18.290 --> 01:19.880 So they're in sequence, right? 20 01:19.880 --> 01:24.410 First you've got the letters, then you've got the number of required symbols, and then you've got 21 01:24.410 --> 01:26.240 the required numbers. 22 01:26.240 --> 01:28.340 So this is the Easy Level. 23 01:28.340 --> 01:30.980 And then there is the Hard Level. 24 01:31.310 --> 01:38.360 And the Hard Level requires you to generate the password in a completely random order. 25 01:38.360 --> 01:46.410 So instead of having it being letter, symbol, number, it should be maybe letter and then a symbol, and 26 01:46.410 --> 01:50.790 then a number, then a letter, then a symbol and then a number. 27 01:51.360 --> 01:59.340 But notice how this is completely random every single time you generate it, the order of where the 28 01:59.340 --> 02:03.180 symbols and where the numbers appear in your password are completely random. 29 02:03.180 --> 02:09.730 So for example, if you look at the demo version, and I do the same thing 4 letters, 2 symbols, 30 02:09.730 --> 02:15.520 2 numbers, where the numbers and where the symbols occur are completely unpredictable. 31 02:15.520 --> 02:17.740 So that's the Hard Level. 32 02:17.740 --> 02:23.770 I recommend trying the Easy Level first, and then once you've managed to do it, then take yourself 33 02:23.770 --> 02:24.850 up to the Hard Level. 34 02:24.850 --> 02:29.230 If you think you're up to it, pause the video now and try to complete the final project. 35 02:37.820 --> 02:44.480 All right, so let's first tackle the Easy Level where we're just generating a password with the required 36 02:44.480 --> 02:45.530 number of letters, 37 02:45.530 --> 02:50.180 and then the required number of symbols, and then the required number of numbers. 38 02:50.180 --> 02:52.730 So let's go ahead and tackle this one first. 39 02:52.920 --> 02:57.150 Now we know that we've got these lists which we can draw from, 40 02:57.150 --> 03:02.640 and we know that we can use the Random Module to get hold of a random item from the list. 41 03:02.640 --> 03:06.780 So all we have to do is first get four random letters. 42 03:06.780 --> 03:12.450 So let's say that we had a password which just started out as an empty string, 43 03:12.570 --> 03:21.540 then we can use a for loop to loop through all of the characters that we need to create for our password. 44 03:21.540 --> 03:31.620 For example, I might say for char, short for character, in the range of...from 1 to the number of 45 03:31.620 --> 03:33.720 letters that the user wanted. 46 03:36.150 --> 03:43.330 So in this case, if the user wanted 4 letters, then it will be a range from 1 to 4, but not including 47 03:43.330 --> 03:43.810 4. 48 03:43.810 --> 03:48.250 So it's actually from 1 to 3, which is only three characters. 49 03:48.250 --> 03:53.770 In order to modify this, we have to do what we did always before, which is just to add one to the 50 03:53.770 --> 03:55.360 end of our range. 51 03:55.360 --> 04:00.880 So now we're going to create a range based on the number of letters that the user wanted. 52 04:00.880 --> 04:04.960 And I'm just going to go along with the assumption that the number of letters equals 4. 53 04:04.960 --> 04:07.550 Let's just pretend that's what the user will enter. 54 04:07.550 --> 04:11.690 So then this range becomes 1 - 4 + 1 which is 5. 55 04:11.690 --> 04:19.120 So the range is in fact going to be 1 - 4. For every single number in that range from 1 to 56 04:19.120 --> 04:23.600 2 to 3 to 4, I'm going to generate them a random letter. 57 04:23.600 --> 04:26.420 And I'm going to pick it out of this list of letters. 58 04:26.420 --> 04:32.040 To do that I can either generate a random number and use it as the index, 59 04:32.040 --> 04:40.320 or you might have seen previously, I showed you the random.choice() function. And inside this random.choice(), 60 04:40.320 --> 04:46.410 we can pass a sequence which in our case is the letters list. 61 04:46.530 --> 04:54.730 Then it will look through this list of letters and it will give us a random item from that list. 62 04:54.880 --> 05:01.330 So now that random letter is going to be something that we're going to need to add to our password, 63 05:01.330 --> 05:01.900 right? 64 05:01.900 --> 05:06.880 So we can set this equal to a random character (random.char). 65 05:07.150 --> 05:10.270 And now let's go ahead and just print it out. 66 05:14.830 --> 05:21.140 So let's say we want 4 letters in our password, and we can type anything for the other ones. 67 05:21.140 --> 05:28.040 But notice how when the for loop runs, it's given us some random characters that it's picked out of 68 05:28.040 --> 05:29.570 our letters list. 69 05:29.600 --> 05:33.770 How can we add each of those letters to our password? 70 05:33.830 --> 05:40.040 Well, we can use the string concatenation that we learned very early on in Day 1. 71 05:40.040 --> 05:46.950 We can say the password equals the previous password plus the random_char 72 05:47.280 --> 05:52.680 Of course, the shortened version of this is just password += random_char. 73 05:52.680 --> 05:54.150 And now let's go ahead, 74 05:54.150 --> 06:00.330 and instead of printing the random_char, let's print the password at each stage of the loop. 75 06:04.530 --> 06:07.660 And again I'm going to choose 4 letters. 76 06:08.080 --> 06:14.860 So you can see the first time the for loop runs I get a capital H as the random_char, and then 77 06:14.860 --> 06:20.500 the next time the loop runs, I get an A and the A is tagged to the end of the H. 78 06:20.500 --> 06:27.520 So I get HA, and so on and so forth until I get these four characters in the beginning of what seems 79 06:27.520 --> 06:31.430 to be my random password that's going to be generated. 80 06:32.990 --> 06:39.770 Now, if you wanted to, you can actually simplify this down to just one step, because instead of having 81 06:39.770 --> 06:45.950 this intermediary, which is the random_char variable, we can simply just replace it with the 82 06:45.950 --> 06:47.930 code like this. 83 06:47.930 --> 06:52.280 So in this case, we're getting a random choice from our letters list, 84 06:52.280 --> 06:56.490 so we get a random letter, and then we add that to our password. 85 06:56.910 --> 07:03.000 Now that we've done that for the letter, then it's pretty easy to see how we can continue doing this 86 07:03.000 --> 07:04.500 for the symbol and the numbers. 87 07:04.500 --> 07:07.560 We just have to keep adding it to the end of our password. 88 07:07.560 --> 07:10.080 So let me quickly write out the code for this. 89 07:18.310 --> 07:24.460 So now when the user requests that they want four letters in their password, then we generate a range 90 07:24.460 --> 07:26.500 from 1 to 5. 91 07:26.500 --> 07:33.670 And then for each of those positions, we generate a random letter in order to fill the password. 92 07:33.670 --> 07:38.260 And then we add on the required number of symbols and the required number of numbers. 93 07:38.260 --> 07:41.650 And finally we print out the final password. 94 07:43.460 --> 07:47.510 Now there's a way to simplify our code even more. 95 07:47.540 --> 07:56.000 Previously, we always used the range by starting from one and then going up to one over the number 96 07:56.000 --> 07:56.690 that we want. 97 07:56.720 --> 08:03.320 For example, when we wanted 1 to 100, we created a range of 1 to 101. 98 08:03.410 --> 08:12.120 Now in this case, because all that we want is a range that covers all the letters, symbols, and numbers 99 08:12.120 --> 08:13.410 that the user wants. 100 08:13.410 --> 08:23.160 So if the user wanted four letters, then what we need the range to be is 1, 2, 3, and 4, 101 08:23.160 --> 08:27.270 which in this case is a range of (1, 5), 102 08:27.270 --> 08:31.380 because of the way that the range doesn't include the upper limit. 103 08:31.410 --> 08:38.610 Now, if we think about this logically, we can also change this to 0, 1, 2, 3 104 08:38.610 --> 08:43.230 So then we can have a range of 0 to 4. 105 08:43.230 --> 08:48.390 So that means we can actually use the number of letters as the upper limit, 106 08:48.390 --> 08:55.240 and then simply change this to 0 so that we don't have to add 1 to our number of letters. 107 08:55.240 --> 09:02.110 And I think this will make our code even simpler and hopefully simpler to understand as well. 108 09:02.140 --> 09:07.660 Now, if you prefer the previous version, which we've seen throughout the course, then feel free to 109 09:07.660 --> 09:08.860 keep it as it is. 110 09:08.860 --> 09:14.530 But this way we get rid of all of these plus ones and you can see it's a lot tidier. 111 09:14.530 --> 09:16.900 Let's go ahead and run this code. 112 09:17.300 --> 09:22.040 And again I'm going to choose 4 letters, 2 numbers, and 2 symbols. 113 09:22.130 --> 09:27.770 And I end up with my final password which fits exactly that criteria, 114 09:27.770 --> 09:29.660 and it looks pretty random. 115 09:29.870 --> 09:37.190 But the only problem is that if a hacker knew that you always have two symbols at this position and 116 09:37.190 --> 09:43.590 two numbers at this position, then it's very easy to crack that password, because in order to get 117 09:43.590 --> 09:49.710 the last digit, for example, they only have to try nine different variations 123456789 118 09:49.710 --> 09:50.580 . 119 09:50.580 --> 09:54.870 And this just limits the strength of your password. 120 09:54.960 --> 10:00.630 In order to tackle that, you would have to tackle it at the Hard Level, which is how do you get a 121 10:00.630 --> 10:06.670 password that has all of these letters and numbers in a completely random order. 122 10:06.970 --> 10:11.980 To do that, we mentioned that you have to do a bit of Googling because it might require something that 123 10:11.980 --> 10:18.670 you haven't done before, but in essence, you've got access to everything you need to perform the logic. 124 10:18.670 --> 10:24.280 So if you haven't given that a go, then this might be a good time to pause and have a think about how 125 10:24.280 --> 10:30.890 you might structure the logic, or how you might create a flow chart to express this logic that you 126 10:30.890 --> 10:31.760 would want. 127 10:32.000 --> 10:36.620 And once you've done that, and if you want to see the solution and walk through it with me, then come 128 10:36.620 --> 10:39.410 back here, and I'll show you how to do it, 129 10:39.410 --> 10:40.940 but first give it a go. 130 10:44.390 --> 10:45.080 All right. 131 10:45.080 --> 10:51.230 In order to tackle the Hard Level, what we essentially need to do is instead of adding each of these 132 10:51.230 --> 10:56.700 letters into a string, we actually want to add it into a list. 133 10:57.270 --> 11:02.610 So I'm going to copy all of this that's here, and I'm just going to comment it out, and I'm going 134 11:02.610 --> 11:06.480 to paste it under my Hard Level and work on it here. 135 11:06.540 --> 11:13.020 So instead of using a password string I'm going to create a list and to better describe it. 136 11:13.020 --> 11:15.930 I'll change my variable name to Password list. 137 11:16.050 --> 11:23.950 So now instead of using password to add each of these letters and numbers and symbols, I'm going to 138 11:23.950 --> 11:25.900 be adding it to my list. 139 11:30.250 --> 11:38.410 Now, to add things to a list, you can use the same syntax that you did with strings, which is to 140 11:38.410 --> 11:44.630 add the new item into the list and to update the old list. 141 11:44.660 --> 11:51.350 You might be more familiar though with the syntax, which is append(), and both of these work. 142 11:51.350 --> 11:57.200 You can use either of them if you want, but they'll end up doing the same thing, which is to add each 143 11:57.200 --> 12:02.120 of those things you've generated in the order that you've generated to your password. 144 12:02.120 --> 12:11.770 So we end up now with a list with four letters, two symbols, and two numbers, all stored as strings 145 12:11.770 --> 12:14.380 because of the quotation marks around them. 146 12:14.740 --> 12:21.280 So now that we've got a list, well, then we have to think about, well, how can we shuffle our list? 147 12:21.280 --> 12:24.580 How can we mess up the order of the items in our list? 148 12:25.090 --> 12:30.310 And that might take you to Google, and you might search for something like how to change the order 149 12:30.310 --> 12:32.950 of items in a list. 150 12:32.950 --> 12:38.860 And then we also have to add our keyword, which is Python, because there's obviously a lot of other 151 12:38.860 --> 12:40.150 programming languages. 152 12:40.150 --> 12:45.280 And we come up against our first StackOverflow question, how can I reorder a list? 153 12:45.310 --> 12:47.980 Well, that sounds kind of like what I want to do, right? 154 12:47.980 --> 12:58.370 So if we scroll down, you can see that the way to do it is either using a for loop like so, or to 155 12:58.370 --> 13:01.220 simply use the shuffle() function. 156 13:01.910 --> 13:10.760 This is a much simpler way, because it allows us to update the existing list just by calling the shuffle() 157 13:10.760 --> 13:17.360 function on it, and this one actually requires us to create a new list, and we have to create a bunch 158 13:17.360 --> 13:22.590 of random numbers for the order and then to reorder them using a for loop. 159 13:22.590 --> 13:26.550 So I'm going to go with this version and let's try it out. 160 13:26.550 --> 13:29.670 Let's print the password list before the shuffle. 161 13:29.670 --> 13:35.070 And then let's use the random.shuffle and pass in the password_list. 162 13:35.070 --> 13:38.760 And then let's print the outcome of that shuffle. 163 13:38.760 --> 13:41.100 So let's print the password_list again. 164 13:42.790 --> 13:45.670 So now you can see that we've got a version before. 165 13:45.670 --> 13:47.530 And then we've got a version after. 166 13:47.530 --> 13:56.170 So if I run my code and I write again 4 letters, 2 symbols, 2 numbers, you can see that previously 167 13:56.170 --> 14:01.870 it was ordered in the order that we added each of the characters, after the shuffle, 168 14:01.870 --> 14:03.850 they're now pretty much random. 169 14:03.850 --> 14:05.830 There's letters in random places, 170 14:05.830 --> 14:07.600 there's are symbols in random places, 171 14:07.600 --> 14:11.440 So if only we could turn this back into a string. 172 14:11.440 --> 14:15.280 Then we've got our password that's nicely shuffled. 173 14:15.280 --> 14:17.980 So how can we turn it back into a string? 174 14:17.980 --> 14:20.950 Well, we could simply use a for loop, right? 175 14:20.950 --> 14:33.560 We could say, "for each char in the password_list..."we're going to add it to a variable called 176 14:33.560 --> 14:38.150 password, which is going to start off again as a empty string. 177 14:38.150 --> 14:40.700 And then we're going to add to it. 178 14:40.700 --> 14:45.950 So we're going to say password += each character in our password_list. 179 14:45.950 --> 14:52.580 And now if I go ahead and just print my final password I'm going to add an f-string as well. 180 14:52.700 --> 14:58.980 Let's say, "Your password is:"...and then let's insert the {password} 181 14:59.790 --> 15:09.390 And now if I run my code and let's say I want 12 letters, 3 symbols and 4 numbers, then 182 15:09.390 --> 15:17.130 it's going to generate me a entire password that's completely randomized in terms of the orders of the 183 15:17.130 --> 15:18.640 symbols and the numbers. 184 15:18.640 --> 15:24.730 And I've now solved the hard part of this challenge project. 185 15:25.150 --> 15:27.100 Did that make sense to you? 186 15:27.130 --> 15:30.460 Did you manage to get it to do what you wanted to do? 187 15:31.780 --> 15:37.870 If you're at all confused about the code that we've covered here, then be sure to check out the final 188 15:37.870 --> 15:42.160 project and take a look at how the Easy Level is implemented, 189 15:42.160 --> 15:47.780 how the Hard Level is implemented, and try switching it around so that you really get to understand 190 15:47.780 --> 15:48.050 it. 191 15:48.050 --> 15:53.510 Try instead of maybe, getting the user to tell you how many letters, how many symbols, how many 192 15:53.510 --> 15:54.230 numbers, 193 15:54.230 --> 16:00.050 instead, just define those yourself or use a random number of letters, numbers, and symbols. 194 16:00.050 --> 16:05.900 Play around with the code until it starts doing what you want it to do, and it starts making sense. 195 16:06.180 --> 16:11.430 But I hope you had fun building this project with me today and learning all about loops. 196 16:11.670 --> 16:16.500 On the next lesson, we're going to be learning more about these things that we've been using a lot, 197 16:16.500 --> 16:19.020 which is Python functions. 198 16:19.020 --> 16:24.960 So I'm going to bid you good night for today, and hopefully I'll see you bright and early tomorrow, 199 16:24.960 --> 16:28.440 and we'll learn some new skills and work on some new projects. 200 16:28.440 --> 16:30.060 So that's all from me. 201 16:30.060 --> 16:31.470 Good night from Angela.