{"id":47,"date":"2015-08-28T11:15:58","date_gmt":"2015-08-28T08:15:58","guid":{"rendered":"https:\/\/amsd.go.ro\/wordpress\/?p=47"},"modified":"2021-09-07T11:26:22","modified_gmt":"2021-09-07T08:26:22","slug":"regular-expression-easy-guide","status":"publish","type":"post","link":"https:\/\/amsd.go.ro\/wordpress\/?p=47","title":{"rendered":"Regular Expression Easy Guide"},"content":{"rendered":"

Summary of regex constructs.<\/p>\n

 <\/div>\n

Characters<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
x<\/code><\/td>\nThe character x<\/td>\n<\/tr>\n
\\<\/code><\/td>\nThe backslash character<\/td>\n<\/tr>\n
\\0n<\/code><\/td>\nThe character with octal value 0n (0 ⇐ n ⇐ 7)<\/td>\n<\/tr>\n
\\0nn<\/code><\/td>\nThe character with octal value 0nn (0 ⇐ n ⇐ 7)<\/td>\n<\/tr>\n
\\0mnn<\/code><\/td>\nThe character with octal value 0mnn (0 ⇐ m ⇐ 3, 0 ⇐ n ⇐ 7)<\/td>\n<\/tr>\n
\\xhh<\/code><\/td>\nThe character with hexadecimal value 0xhh<\/td>\n<\/tr>\n
\\uhhhh<\/code><\/td>\nThe character with hexadecimal value 0xhhhh<\/td>\n<\/tr>\n
\\x{h…h}<\/code><\/td>\nThe character with hexadecimal value 0xh…h (Character.MIN_CODE_POINT  ⇐ 0xh…h ⇐  Character.MAX_CODE_POINT)<\/td>\n<\/tr>\n
\\t<\/code><\/td>\nThe tab character ('\\u0009')<\/code><\/td>\n<\/tr>\n
\\n<\/code><\/td>\nThe newline (line feed) character ('\\u000A')<\/code><\/td>\n<\/tr>\n
\\r<\/code><\/td>\nThe carriage-return character ('\\u000D')<\/code><\/td>\n<\/tr>\n
\\f<\/code><\/td>\nThe form-feed character ('\\u000C')<\/code><\/td>\n<\/tr>\n
\\a<\/code><\/td>\nThe alert (bell) character ('\\u0007')<\/code><\/td>\n<\/tr>\n
\\e<\/code><\/td>\nThe escape character ('\\u001B')<\/code><\/td>\n<\/tr>\n
\\cx<\/code><\/td>\nThe control character corresponding to x<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Character classes<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n\n
[abc]<\/code><\/td>\na, b, or c (simple class)<\/td>\n<\/tr>\n
[^abc]<\/code><\/td>\nAny character except a, b, or c (negation)<\/td>\n<\/tr>\n
[a-zA-Z]<\/code><\/td>\na through z or A through Z, inclusive (range)<\/td>\n<\/tr>\n
[a-d[m-p]]<\/code><\/td>\na through d, or m through p: [a-dm-p]<\/code> (union)<\/td>\n<\/tr>\n
[a-z&&[def]]<\/code><\/td>\nd, e, or f (intersection)<\/td>\n<\/tr>\n
[a-z&&[^bc]]<\/code><\/td>\na through z, except for b and c: [ad-z]<\/code> (subtraction)<\/td>\n<\/tr>\n
[a-z&&[^m-p]]<\/code><\/td>\na through z, and not m through p: [a-lq-z]<\/code> (subtraction)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Predefined character classes<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n\n
.<\/code><\/td>\nAny character (may or may not match line terminators)<\/td>\n<\/tr>\n
\\d<\/code><\/td>\nA digit: [0-9]<\/code><\/td>\n<\/tr>\n
\\D<\/code><\/td>\nA non-digit: [^0-9]<\/code><\/td>\n<\/tr>\n
\\s<\/code><\/td>\nA whitespace character: [ \\t\\n\\x0B\\f\\r]<\/code><\/td>\n<\/tr>\n
\\S<\/code><\/td>\nA non-whitespace character: [^\\s]<\/code><\/td>\n<\/tr>\n
\\w<\/code><\/td>\nA word character: [a-zA-Z_0-9]<\/code><\/td>\n<\/tr>\n
\\W<\/code><\/td>\nA non-word character: [^\\w]<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

POSIX character classes<\/h2>\n
\n

POSIX character classes (US-ASCII<\/abbr> only)<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\\p{Lower}<\/code><\/td>\nA lower-case alphabetic character: [a-z]<\/code><\/td>\n<\/tr>\n
\\p{Upper}<\/code><\/td>\nAn upper-case alphabetic character: [A-Z]<\/code><\/td>\n<\/tr>\n
\\p{ASCII<\/abbr>}<\/code><\/td>\nAll ASCII<\/abbr>: [\\x00-\\x7F]<\/code><\/td>\n<\/tr>\n
\\p{Alpha}<\/code><\/td>\nAn alphabetic character: [\\p{Lower}\\p{Upper}]<\/code><\/td>\n<\/tr>\n
\\p{Digit}<\/code><\/td>\nA decimal digit: [0-9]<\/code><\/td>\n<\/tr>\n
\\p{Alnum}<\/code><\/td>\nAn alphanumeric character: [\\p{Alpha}\\p{Digit}]<\/code><\/td>\n<\/tr>\n
\\p{Punct}<\/code><\/td>\nPunctuation: One of !”#$%&'()*+,-.\/:;⇔?@[\\]^_`{|}~<\/code><\/td>\n<\/tr>\n
\\p{Graph}<\/code><\/td>\nA visible character: [\\p{Alnum}\\p{Punct}]<\/code><\/td>\n<\/tr>\n
\\p{Print}<\/code><\/td>\nA printable character: [\\p{Graph}\\x20]<\/code><\/td>\n<\/tr>\n
\\p{Blank}<\/code><\/td>\nA space or a tab: [ \\t]<\/code><\/td>\n<\/tr>\n
\\p{Cntrl}<\/code><\/td>\nA control character: [\\x00-\\x1F\\x7F]<\/code><\/td>\n<\/tr>\n
\\p{XDigit}<\/code><\/td>\nA hexadecimal digit: [0-9a-fA-F]<\/code><\/td>\n<\/tr>\n
\\p{Space}<\/code><\/td>\nA whitespace character: [ \\t\\n\\x0B\\f\\r]<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Classes for Unicode<\/h2>\n
\n

Classes for Unicode scripts, blocks, categories and binary properties<\/p>\n

\n\n\n\n\n\n\n\n\n\n
\\p{IsLatin}<\/code><\/td>\nA Latin script character (script)<\/td>\n<\/tr>\n
\\p{InGreek}<\/code><\/td>\nA character in the Greek block (block)<\/td>\n<\/tr>\n
\\p{Lu}<\/code><\/td>\nAn uppercase letter (category)<\/td>\n<\/tr>\n
\\p{IsAlphabetic}<\/code><\/td>\nAn alphabetic character (binary property)<\/td>\n<\/tr>\n
\\p{Sc}<\/code><\/td>\nA currency symbol<\/td>\n<\/tr>\n
\\P{InGreek}<\/code><\/td>\nAny character except one in the Greek block (negation)<\/td>\n<\/tr>\n
[\\p{L}&&[^\\p{Lu}]]<\/code> <\/td>\nAny letter except an uppercase letter (subtraction)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Boundary matchers<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n\n\n
^<\/code><\/td>\nThe beginning of a line<\/td>\n<\/tr>\n
$<\/code><\/td>\nThe end of a line<\/td>\n<\/tr>\n
\\b <\/code><\/td>\nA word boundary<\/td>\n<\/tr>\n
\\B<\/code><\/td>\nA non-word boundary<\/td>\n<\/tr>\n
\\A<\/code><\/td>\nThe beginning of the input<\/td>\n<\/tr>\n
\\G<\/code><\/td>\nThe end of the previous match<\/td>\n<\/tr>\n
\\Z<\/code><\/td>\nThe end of the input but for the final terminator, if any<\/td>\n<\/tr>\n
\\z<\/code><\/td>\nThe end of the input<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Greedy quantifiers<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n
X?<\/code><\/td>\nX, once or not at all<\/td>\n<\/tr>\n
X*<\/code><\/td>\nX, zero or more times<\/td>\n<\/tr>\n
X+<\/code><\/td>\nX, one or more times<\/td>\n<\/tr>\n
X{n}<\/code><\/td>\nX, exactly n times<\/td>\n<\/tr>\n
X{n,}<\/code><\/td>\nX, at least n times<\/td>\n<\/tr>\n
X{n,m}<\/code><\/td>\nX, at least n but not more than m times<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Reluctant quantifiers<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n
X??<\/code><\/td>\nX, once or not at all<\/td>\n<\/tr>\n
X*?<\/code><\/td>\nX, zero or more times<\/td>\n<\/tr>\n
X+?<\/code><\/td>\nX, one or more times<\/td>\n<\/tr>\n
X{n}?<\/code><\/td>\nX, exactly n times<\/td>\n<\/tr>\n
X{n,}?<\/code><\/td>\nX, at least n times<\/td>\n<\/tr>\n
X{n,m}?<\/code><\/td>\nX, at least n but not more than m times<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Possessive quantifiers<\/h2>\n
\n
\n\n\n\n\n\n\n\n\n
X?+<\/code><\/td>\nX, once or not at all<\/td>\n<\/tr>\n
X*+<\/code><\/td>\nX, zero or more times<\/td>\n<\/tr>\n
X++<\/code><\/td>\nX, one or more times<\/td>\n<\/tr>\n
X{n}+<\/code><\/td>\nX, exactly n times<\/td>\n<\/tr>\n
X{n,}+<\/code><\/td>\nX, at least n times<\/td>\n<\/tr>\n
X{n,m}+<\/code><\/td>\nX, at least n but not more than m times<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Logical operators<\/h2>\n
\n
\n\n\n\n\n\n
XY<\/code><\/td>\nX followed by Y<\/td>\n<\/tr>\n
X|Y<\/code><\/td>\nEither X or Y<\/td>\n<\/tr>\n
(X)<\/code><\/td>\nX, as a capturing group<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Back references<\/h2>\n
\n
\n\n\n\n\n
\\n<\/code><\/td>\nWhatever the nth capturing group matched<\/td>\n<\/tr>\n
\\k<name><\/code><\/td>\nWhatever the named-capturing group “name” matched<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Quotation<\/h2>\n
\n
\n\n\n\n\n\n
\\<\/code><\/td>\nNothing, but quotes the following character<\/td>\n<\/tr>\n
\\Q<\/code><\/td>\nNothing, but quotes all characters until \\E<\/code><\/td>\n<\/tr>\n
\\E<\/code><\/td>\nNothing, but ends quoting started by \\Q<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n
 <\/div>\n

Special constructs<\/h2>\n

Special constructs (named-capturing and non-capturing)<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
(?<name>X)<\/code><\/td>\nX, as a named-capturing group<\/td>\n<\/tr>\n
(?:X)<\/code><\/td>\nX, as a non-capturing group<\/td>\n<\/tr>\n
(?idmsuxU-idmsuxU)<\/code> <\/td>\nNothing, but turns match flags i d m s u x U on – off<\/td>\n<\/tr>\n
(?idmsux-idmsux:X)<\/code>  <\/td>\nX, as a non-capturing group with the given flags i d m s u x on – off<\/td>\n<\/tr>\n
(?=X)<\/code><\/td>\nX, via zero-width positive lookahead<\/td>\n<\/tr>\n
(?!X)<\/code><\/td>\nX, via zero-width negative lookahead<\/td>\n<\/tr>\n
(?⇐X)<\/code><\/td>\nX, via zero-width positive lookbehind<\/td>\n<\/tr>\n
(?<!X)<\/code><\/td>\nX, via zero-width negative lookbehind<\/td>\n<\/tr>\n
(?>X)<\/code><\/td>\nX, as an independent, non-capturing group<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"

Summary of regex constructs.   Characters x The character x \\ The backslash character \\0n The character with octal value 0n (0 ⇐ n ⇐ 7) \\0nn The character with octal value 0nn (0 ⇐ n ⇐ 7) \\0mnn The character with octal value 0mnn (0 ⇐ m ⇐ 3, 0 ⇐ n ⇐ 7) \\xhh […]<\/p>\n

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