====== Regex ======
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Platforma testująca: [[https://regexr.com/]]\\
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=== Metacharacters ===
Metacharacters are characters with a special meaning:

^ Character ^ Description ^ Example ^
| ''[]'' | A set of characters | ''[a-m]'' |
| ''\'' | Signals a special sequence (can also be used to escape special characters) | ''\d'' |
| ''.'' | Any character (except newline character) | ''he..o'' |
| ''^'' | Starts with | ''^hello'' |
| ''$'' | Ends with | ''planet$'' |
| ''*'' | Zero or more occurrences | ''he.*o'' |
| ''+'' | One or more occurrences | ''he.+o'' |
| ''?'' | Zero or one occurrences | ''he.?o'' |
| ''{}'' | Exactly the specified number of occurrences | ''he.{2}o'' |
| ''|'' | Either or | ''falls|stays'' |
| ''()'' | Capture and group ||
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=== Brackets ===
Brackets are used to find a range of characters:

^ Bracket ^ Description ^
| ''[abc]'' | Find any character between the brackets |
| ''[^abc]'' | Find any character NOT between the brackets |
| ''[0-9]'' | Find any character between the brackets (any digit) |
| ''[^0-9]'' | Find any character NOT between the brackets (any non-digit) |
| ''(x|y)'' | Find any of the alternatives specified |
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=== Special Sequences ===
A special sequence is a ''\'' followed by one of the characters in the list below, and has a special meaning:

^ Character ^ Description ^ Example ^
| ''\A'' | Returns a match if the specified characters are at the beginning of the string | ''\AThe'' |
| ''\b'' | Returns a match where the specified characters are at the beginning or at the end of a word \\ (the "r" in the beginning is making sure that the string is being treated as a "raw string") | ''\bain'' \\ ''ain\b'' |
| ''\B'' | Returns a match where the specified characters are present, but NOT at the beginning (or at the end) of a word \\ (the "r" in the beginning is making sure that the string is being treated as a "raw string") | ''\Bain'' \\ ''ain\B'' |
| ''\d'' | Returns a match where the string contains digits (numbers from 0-9) | ''\d'' |
| ''\D'' | Returns a match where the string DOES NOT contain digits | ''\D'' |
| ''\s'' | Returns a match where the string contains a white space character | ''\s'' |
| ''\S'' | Returns a match where the string DOES NOT contain a white space character | ''\S'' |
| ''\w'' | Returns a match where the string contains any word characters (characters from a to Z, digits from 0-9, and the underscore _ character) | ''\w'' |
| ''\W'' | Returns a match where the string DOES NOT contain any word characters | ''\W'' |
| ''\Z'' | Returns a match if the specified characters are at the end of the string | ''Spain\Z'' |
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=== Sets ===
A set is a set of characters inside a pair of square brackets ''[]'' with a special meaning:

^ Set ^ Description ^
| ''[arn]'' | Returns a match where one of the specified characters (''a'', ''r'', or ''n'') is present |
| ''[a-n]'' | Returns a match for any lower case character, alphabetically between ''a'' and ''n'' |
| ''[^arn]'' | Returns a match for any character EXCEPT ''a'', ''r'', and ''n'' |
| ''[0123]'' | Returns a match where any of the specified digits (''0'', ''1'', ''2'', or ''3'') are present |
| ''[0-9]'' | Returns a match for any digit between 0 and 9 |
| ''[0-5][0-9]'' | Returns a match for any two-digit numbers from 00 and 59 |
| ''[a-zA-Z]'' | Returns a match for any character alphabetically between a and z, lower case OR upper case |
| ''[+]'' | In sets, ''+'', ''*'', ''.'', ''|'', ''()'', ''$'', ''{}'' has no special meaning, so ''[+]'' means: return a match for any ''+'' character in the string |