1 00:00:01,300 --> 00:00:04,280 Wildcards are used for pattern matching. 2 00:00:04,470 --> 00:00:09,490 Thanks to them we can use for example one month for multiple files. 3 00:00:10,350 --> 00:00:14,240 This can be best described by some examples so just keep watching. 4 00:00:14,310 --> 00:00:22,850 And we will see it in action Vout guts can be used by many comments as C.P and us move. 5 00:00:22,950 --> 00:00:25,900 And also for string comparison in beshe. 6 00:00:25,920 --> 00:00:33,190 But how world Garretts looks like those are most common wildcards from the beginning. 7 00:00:33,260 --> 00:00:39,530 It is nearly impossible to remember what the wild card symbols means but you really used to it very 8 00:00:39,530 --> 00:00:41,380 quickly by practicing. 9 00:00:41,630 --> 00:00:50,270 So now let's go quickly through each symbol question mark represents single character. 10 00:00:50,270 --> 00:00:55,420 So if you write hell question mark it can match help. 11 00:00:55,610 --> 00:01:07,020 Hell or hell one for example next symbol is an asterisk which represents any number of characters. 12 00:01:07,210 --> 00:01:20,010 It means even zero characters so C-8 asterisk can match car C.A. carpeted carpenter. 13 00:01:20,090 --> 00:01:30,920 Then we have square brackets which represent single character from Orange Fire 0 dash to Menchie's files 14 00:01:30,970 --> 00:01:34,220 0 5 7 and 5 2. 15 00:01:34,640 --> 00:01:41,420 If we don't do the Desch symbol between characters in square brackets then the batter imageries single 16 00:01:41,420 --> 00:01:51,140 character from possible options for example a DD in square brackets followed by it all matches hello 17 00:01:51,380 --> 00:01:53,510 or D.O.. 18 00:01:53,610 --> 00:02:00,140 So here we are choosing only one symbol from symbol specified in square brackets. 19 00:02:01,840 --> 00:02:07,740 Next symbol is currently Breguet which is used for comma separate terms. 20 00:02:08,020 --> 00:02:17,080 We can for example inside curly brackets specify two wild cards separated by a comma asterisk dot text 21 00:02:17,350 --> 00:02:20,080 and that is don't believe. 22 00:02:20,230 --> 00:02:27,670 And as a result we got all files which ends with a txt extension and biddie of extension. 23 00:02:27,680 --> 00:02:34,410 Now it may be hard to understand but when you try it you will find it quite easy. 24 00:02:34,440 --> 00:02:41,970 The last symbol is exclamation mark inside square brackets which means show any character are not listed 25 00:02:42,060 --> 00:02:43,720 in square brackets. 26 00:02:44,040 --> 00:02:51,900 So file exclamation mark Guam will match file two files three but not file one. 27 00:02:53,950 --> 00:02:57,850 We can also use some useful character classes. 28 00:02:57,910 --> 00:03:04,010 The most common are upper which means any uppercase character. 29 00:03:04,180 --> 00:03:10,050 Then we have a flower which means any lower case character. 30 00:03:10,300 --> 00:03:17,510 If we want to match any alphabetic character we use our fire for numbers. 31 00:03:17,650 --> 00:03:30,100 We are using digits plus a whole class basically means Alpha plus digit class together and space class 32 00:03:30,190 --> 00:03:35,790 means any whitespace character space stop or a new line. 33 00:03:35,810 --> 00:03:42,520 So now we have covered a lot and you may be a little overwhelmed by it but you will see that once you 34 00:03:42,530 --> 00:03:46,180 start practicing it it is quite easy. 35 00:03:46,190 --> 00:03:53,820 Now let's check how to use the wildcards in string comparison for string comparison with the wildcard. 36 00:03:53,870 --> 00:04:01,240 We need to use double square brackets double equal sign is not necessary but recommended. 37 00:04:01,370 --> 00:04:09,130 I am personally using it because it tells me that I am not doing a basic string comparison by using 38 00:04:09,130 --> 00:04:18,290 a comparison with wildcards and here is example of how such a string comparison to wild cards can look 39 00:04:18,350 --> 00:04:19,160 in action. 40 00:04:20,260 --> 00:04:21,390 We have covered a lot. 41 00:04:21,430 --> 00:04:24,910 So now let's break it on some examples.