1 00:00:01,010 --> 00:00:05,090 All right guys when the last video we started to get into regular expressions we looked at some of these 2 00:00:05,090 --> 00:00:12,230 Medak characters symbols like the carrot to start with the number assigned to end with the dot the asterisk 3 00:00:12,260 --> 00:00:14,900 and the optional question mark character. 4 00:00:14,900 --> 00:00:19,430 So now what I want to do is get into character sets using brackets. 5 00:00:19,430 --> 00:00:25,340 So we're going to go down here and let's say I want to sort of format this nicely for you guys so you 6 00:00:25,340 --> 00:00:27,110 can have it as a reference. 7 00:00:27,470 --> 00:00:28,420 All of this code. 8 00:00:28,430 --> 00:00:33,830 I mean this course has been pretty modular except for the project so you know if you need to go back 9 00:00:33,830 --> 00:00:38,870 and look at something I want to make it so that it's easy for you to reference and find where you need 10 00:00:39,440 --> 00:00:44,480 so brackets are basically character sets. 11 00:00:45,170 --> 00:00:51,560 So let's let's look at this example that we did with the optional A and E in gray. 12 00:00:51,560 --> 00:01:00,560 So what we can do here is we can say re schools are ex-Russian let's make it case insensitive and we'll 13 00:01:00,560 --> 00:01:05,390 say G R and let's just do G R A Y. 14 00:01:05,390 --> 00:01:10,360 Now we know that this we want this to be able to be in a or an e. 15 00:01:10,680 --> 00:01:17,270 OK so what we can do is we can use brackets here and then anything we put in here like a and e means 16 00:01:17,270 --> 00:01:23,060 that whatever this character is has to be whatever one of whatever is in here. 17 00:01:23,060 --> 00:01:23,440 OK. 18 00:01:23,450 --> 00:01:25,710 So it can be an A or an E. 19 00:01:26,090 --> 00:01:35,090 All right so what we're going to do is actually we just put a comment here and I'll say must be in a 20 00:01:35,690 --> 00:01:37,170 or e. 21 00:01:37,790 --> 00:01:46,190 OK so then let's get rid of this question mark here and let's save that and see what we get so you can 22 00:01:46,190 --> 00:01:48,500 see it works at matches. 23 00:01:48,500 --> 00:01:56,000 If I were to put an e here that matches if I were to get rid of that and save that gives us null so 24 00:01:56,360 --> 00:01:59,060 this is a better solution than this. 25 00:01:59,210 --> 00:02:05,250 Even though we can use a or e here in this case we could also put nothing. 26 00:02:05,450 --> 00:02:10,460 But when we use the character set it has to be in a or an e. 27 00:02:10,460 --> 00:02:14,410 If I were to put it let's say a W that's not going to work. 28 00:02:14,580 --> 00:02:15,880 OK. 29 00:02:16,650 --> 00:02:18,400 What is going on here. 30 00:02:18,440 --> 00:02:18,690 OK. 31 00:02:18,710 --> 00:02:21,250 So has to be an E or an AK. 32 00:02:21,470 --> 00:02:21,890 All right. 33 00:02:21,890 --> 00:02:25,830 Now let's let's see. 34 00:02:25,850 --> 00:02:31,820 Let's go ahead and push this down and let's put this let's do a character set at the beginning so what 35 00:02:31,820 --> 00:02:42,350 I'll do is let's put right here some brackets and then let's say this has to be a G or an F and this 36 00:02:42,350 --> 00:02:44,770 can be case sensitive. 37 00:02:44,770 --> 00:02:51,220 If we get rid of that so let's change this to an A and let's save that run it. 38 00:02:51,230 --> 00:02:57,770 So basically this has to be either a G in uppercase G or an upper case f. 39 00:02:57,830 --> 00:03:05,340 So I'll say must be a G or F so that works. 40 00:03:05,390 --> 00:03:08,650 Let's change it to fray upper uppercase. 41 00:03:08,690 --> 00:03:15,580 That works let's change it to x ray upper case doesn't work because it's not a G or an F. 42 00:03:15,710 --> 00:03:18,800 If we do a lower case g doesn't work. 43 00:03:18,800 --> 00:03:23,290 But again if we add the case insensitive flag that will work. 44 00:03:23,420 --> 00:03:23,750 All right. 45 00:03:23,750 --> 00:03:26,000 Hopefully that makes sense. 46 00:03:26,000 --> 00:03:31,590 Now another thing we can do here let's bring this down. 47 00:03:31,760 --> 00:03:36,980 We could put a carrot symbol inside of the brackets here. 48 00:03:36,980 --> 00:03:37,280 All right. 49 00:03:37,280 --> 00:03:50,310 So if we were to do that what this means is that it'll match anything except a G or F.. 50 00:03:50,630 --> 00:03:51,500 OK. 51 00:03:51,800 --> 00:03:54,140 So it's basically the opposite of this. 52 00:03:54,140 --> 00:04:01,850 So if I were to say Gray doesn't actually didn't matter if this was lowercase or upper case but if we 53 00:04:01,850 --> 00:04:03,000 say that we're going to. 54 00:04:03,000 --> 00:04:06,610 No because it is just an F. 55 00:04:06,620 --> 00:04:10,120 If I were to do an F We'll also get now not a match. 56 00:04:10,130 --> 00:04:17,090 If I were to do an x we're gonna get it's going to pass because this tells it that it can be anything 57 00:04:17,090 --> 00:04:18,400 except this. 58 00:04:18,410 --> 00:04:22,430 Now don't get confused by this meaning it has to start with G and f.. 59 00:04:22,670 --> 00:04:27,500 If that were the case then we would put it on this side. 60 00:04:28,010 --> 00:04:28,340 All right. 61 00:04:28,340 --> 00:04:34,520 So if I were to move that over here outside of the brackets that just means that it has to begin with 62 00:04:34,520 --> 00:04:36,990 a year and a half and you'll see that passes. 63 00:04:37,010 --> 00:04:41,230 So don't get that confused if it's inside that means basically not. 64 00:04:41,240 --> 00:04:44,270 So not a G or an F. 65 00:04:44,720 --> 00:04:45,020 All right. 66 00:04:45,020 --> 00:04:50,270 Now let's say that we want that to be any upper case letter. 67 00:04:50,270 --> 00:04:57,680 So I'm going to remove the case insensitive flag and and here we can do a range so we could do a uppercase 68 00:04:57,770 --> 00:05:00,670 a dash Z. 69 00:05:01,100 --> 00:05:01,490 All right. 70 00:05:01,490 --> 00:05:04,310 So this can match any I'll say any 71 00:05:06,680 --> 00:05:11,980 uppercase letter and we'll save an x ray matches. 72 00:05:12,010 --> 00:05:12,460 OK. 73 00:05:12,470 --> 00:05:16,010 Gray matches frais matches. 74 00:05:16,340 --> 00:05:19,010 If I do a lower case that's not going to match. 75 00:05:19,100 --> 00:05:23,910 OK because these are upper case and there's no case insensitive flag. 76 00:05:24,350 --> 00:05:36,080 If we wanted to do lowercase we could do lowercase a to lowercase c and this will match any lower case 77 00:05:36,080 --> 00:05:39,610 letters so if I save that phrase will pass. 78 00:05:39,650 --> 00:05:44,180 If I put in lowercase x ray that will pass as well. 79 00:05:44,180 --> 00:05:50,480 Now if you want it to be any letter at all whether it's uppercase or lowercase what you could do is 80 00:05:50,480 --> 00:05:57,030 you could say capital A to capital Z and then leave the lower case a to lower case. 81 00:05:57,050 --> 00:06:02,020 So this will match any letter of any case. 82 00:06:02,030 --> 00:06:10,360 So if we go ahead and save that matches if I change this to an uppercase x ray that also matches. 83 00:06:10,550 --> 00:06:12,900 Now we can also do number ranges. 84 00:06:13,070 --> 00:06:25,040 So if I were to do a dash and in here let's say 0 through 9 and then I don't know Ray which doesn't 85 00:06:25,040 --> 00:06:27,950 really make much sense but it's just an example. 86 00:06:27,980 --> 00:06:40,950 So this will match any any digit so if I were to say x ray that's not going to work if I were to say 87 00:06:41,040 --> 00:06:44,140 one day that'll work OK. 88 00:06:44,190 --> 00:06:48,330 So anything between 0 9 we can make this 0 to 3 if we want. 89 00:06:48,330 --> 00:06:53,510 And if I were to put a 4 that's not going to work so you can put whatever range you want but zero to 90 00:06:53,520 --> 00:06:55,770 nine will be all digits. 91 00:06:55,860 --> 00:06:56,350 OK. 92 00:06:56,400 --> 00:07:05,340 If I were to do 10 that that also works because what it's doing is it's looking at from here over. 93 00:07:05,760 --> 00:07:07,220 OK. 94 00:07:07,650 --> 00:07:14,730 Now we could put 0 3 9 0 through 9 again and save and look at the match now. 95 00:07:14,730 --> 00:07:16,970 Now it's 1 0 OK. 96 00:07:17,070 --> 00:07:18,560 OK. 97 00:07:19,010 --> 00:07:25,670 And I didn't mention this but you can do you know as many expressions as you want. 98 00:07:25,720 --> 00:07:30,190 OK so this would be one letter and we could do another eight Izzi and so on. 99 00:07:30,240 --> 00:07:34,160 But that's kind of a that's a long way of doing it. 100 00:07:34,500 --> 00:07:41,090 There's an easier way and that's using quantifiers which are used with by using curly braces. 101 00:07:41,100 --> 00:07:41,370 All right. 102 00:07:41,370 --> 00:07:48,280 So let's say Brace's let's braces. 103 00:07:49,970 --> 00:07:51,650 And these are quantifiers. 104 00:07:51,900 --> 00:07:56,700 So let's go back to our Hello expression souls. 105 00:07:56,790 --> 00:08:12,090 H E L L O and say re equals power case insensitive flag and let's do h e l o n save. 106 00:08:12,090 --> 00:08:13,820 And of course that matches. 107 00:08:13,860 --> 00:08:19,680 Now let's say that we wanted Ray here to specify two L's. 108 00:08:19,770 --> 00:08:28,260 So what we could do is is put in our quantifier using curly braces and then the number two and then 109 00:08:28,350 --> 00:08:28,780 l. 110 00:08:28,800 --> 00:08:32,120 OK so it's going to look at the character after it. 111 00:08:32,190 --> 00:08:40,640 So it's going save that I'm sorry it's the character before it so l should actually go for it and save 112 00:08:40,650 --> 00:08:43,290 and that matches because there's two elves. 113 00:08:43,290 --> 00:08:47,720 Now if I were to put an extra L make it three and save that doesn't match. 114 00:08:47,730 --> 00:08:52,470 If I were to put one l in save that doesn't match it has to be exactly 2. 115 00:08:52,470 --> 00:08:53,820 In this case. 116 00:08:53,970 --> 00:09:00,610 All right so let's put a comment here and let's say must occur. 117 00:09:01,680 --> 00:09:03,780 Exactly. 118 00:09:03,860 --> 00:09:09,950 Am am just is just a variable amount of times. 119 00:09:10,590 --> 00:09:14,860 OK so let's go ahead and bring this down. 120 00:09:14,970 --> 00:09:20,220 And now we can also do ranges so let's say we want to call him a 4. 121 00:09:20,220 --> 00:09:23,890 So what this means is that we can have two to four owls. 122 00:09:24,060 --> 00:09:30,420 So if I go ahead and run this with three L's that works if I do an extra outlets for that works if I 123 00:09:30,420 --> 00:09:33,830 do an extra which is five does not work. 124 00:09:34,240 --> 00:09:36,980 OK if I do one does not work. 125 00:09:37,140 --> 00:09:42,650 So this means that it has to be between this amount and this amount. 126 00:09:42,750 --> 00:09:43,050 All right. 127 00:09:43,050 --> 00:09:50,240 And then another thing we can do using quantifiers is we can do just two comma. 128 00:09:50,400 --> 00:09:53,200 And what this means is it must occur. 129 00:09:55,180 --> 00:09:56,260 At least 130 00:09:59,290 --> 00:10:03,430 at least and times OK so at least two times. 131 00:10:03,450 --> 00:10:10,060 So if I go h l l o that will of course work if I do you know 10 of them. 132 00:10:10,060 --> 00:10:21,170 That also works if I do one that doesn't work because it has to be at least two ells OK so that those 133 00:10:21,170 --> 00:10:22,690 are quantifiers. 134 00:10:23,600 --> 00:10:26,630 And then the last thing I want to show you is parentheses 135 00:10:30,230 --> 00:10:36,260 parentheses and these are use for grouping. 136 00:10:37,130 --> 00:10:46,040 So for instance if I were to say really rules and here let's say we wanted and you can use these with 137 00:10:46,040 --> 00:10:49,760 quantifiers that's that's one of the main reasons to use these. 138 00:10:49,820 --> 00:10:59,600 Let's say that I wanted a number between 0 and 9 followed by X and I wanted that three times. 139 00:10:59,600 --> 00:11:00,410 OK. 140 00:11:00,530 --> 00:11:06,620 Now doing it this way this three is only looking at this x right here so it's only it's going to look 141 00:11:06,620 --> 00:11:08,950 at a number and then x three times. 142 00:11:09,020 --> 00:11:17,120 But I want a number x number x number x three times so that for that to happen I would group this these 143 00:11:17,150 --> 00:11:19,800 together with parentheses. 144 00:11:19,820 --> 00:11:28,540 So now for going on here and I say 3 x 3 x 3 x and say that's going to match. 145 00:11:28,550 --> 00:11:36,140 Now if I do another X that's also going to work because it's just looking at the first three if I wanted 146 00:11:36,140 --> 00:11:42,890 to I could put a money sign up here to make sure that it. 147 00:11:42,930 --> 00:11:46,450 And after the third after three Xs. 148 00:11:46,460 --> 00:11:53,250 So now if I save that works but if I add another 3 x 6 or 2 149 00:11:55,890 --> 00:11:57,760 0 because. 150 00:11:57,770 --> 00:11:59,510 Yeah because now it's just looking at the end. 151 00:11:59,510 --> 00:12:02,110 So we'll have to do beginning. 152 00:12:02,110 --> 00:12:06,680 So we'll put a carrot here and see that and that does not work. 153 00:12:06,680 --> 00:12:10,780 So now it has to be exactly 3 x 3 times. 154 00:12:11,110 --> 00:12:12,240 OK. 155 00:12:12,710 --> 00:12:16,960 So you'll you use the carrot and the money sign quite a bit. 156 00:12:17,060 --> 00:12:20,370 When you're using regular expressions. 157 00:12:20,390 --> 00:12:20,660 All right. 158 00:12:20,660 --> 00:12:24,890 Now there's a whole another part of regular expressions that I want to go over real quick and that's 159 00:12:24,890 --> 00:12:27,250 shorthand character classes. 160 00:12:27,560 --> 00:12:36,110 If we want to search for a letter or I'm sorry a word character or a digit or a whitespace character 161 00:12:36,110 --> 00:12:38,900 we can do that with the shorthand character class. 162 00:12:38,900 --> 00:12:40,900 So that's what we're going to look into next.