Regular Expression Cheat Sheet

Nov 3rd, 2015 at 11:10 AM

Regular Expression Cheat Sheet

        Meta-characters
        Description
      
        A

        Matches only at the beginning of the string.

        

        Matches a word boundary.

        B

        Matches anything but a word boundary.

        d

        Matches a digit character. This is the same as [0-9].

        D

        Matches a non-digit character.

        s

        Matches a white-space character.

        S

        Matches a nonwhite-space character.

        [ ]

        Encloses a character range

        ( )

        Encloses a character grouping or defines a back reference.

        $

        Matches the end of the line.

        ^

        Matches the beginning of the line.

        ^

        Matches any character except for the newline

        Quotes the next meta-character.

        w

        Matches any string containing solely underscore and alphanumeric characters. This is the same as [a-zA-Z0-9_]

        W

        Matches a string, omitting the underscore and alphanumeric characters.

        .

        Matches any string except some special symbol and white space character.

        Quantifiers
        Description
      
        +

        Matches at least one character.

        *

        Matches zero or more characters.

        ?

        Matches only zero or one character

        {m}

        Matches exactly m number of characters.

        {m,}

        Matches ranging from m to unlimited number of characters.

        {m,n}

        Matches ranging m to n number of characters.

        Modifiers
        Description
      
        I

        Perform a case-insensitive search.

        G

        Find all occurrences (perform a global search).

        M

        Treat a string as (m for multiple) several lines.

        S

        Treat a string as a single line, ignoring any newline characters found within; this accomplishes just the opposite of the m modifier.

        X

        Ignore white space and comments within the regular expression.

        U

        Stop at the first match. Matches the pattern as many times as possible rather than just stop at the first match.

        Predefined Character Ranges
        Description
      
        [:alpha:]

        Lowercase and uppercase alphabetical characters. This can also be specified as [A-Za-z].

        [:alnum:]

        Lowercase and uppercase alphabetical characters and numberical digits. This can also be specified as [A-Za-z0-9].

        [:cntrl:]

        Control characters such as tab,escape, or backspace.

        [:digit:]

        Numerical digits 0 through 9. This can also be specified as [0-9].

        [:graph:]

        Printable characters found in the range of ASCII 33 to 126.

        [:lower:]

        Lowercase alphabetical characters. This can also be specified as [a-z].

        [:punct:]

        Punctuation characters, including ~ ` ! @ # $ % &amp; * ( ) - _ + = { } [ ] : ; ' &lt; &gt; , . ? and /.

        [:upper:]

        Uppercase alphabetical characters. This can also be specified as [a-z].

        [:space:]

        White-space characters, including the space, horizontal tab, vertical tab, new line, form feed, aor carriage return.

        [:xdigit:]

        Hexadecimal characters, This can also be specified as [a-fA-F0-9].

Some of useful  regular expression
Regular Expression for web developer

Meta-characters	Description
A	Matches only at the beginning of the string.
	Matches a word boundary.
B	Matches anything but a word boundary.
d	Matches a digit character. This is the same as [0-9].
D	Matches a non-digit character.
s	Matches a white-space character.
S	Matches a nonwhite-space character.
[ ]	Encloses a character range
( )	Encloses a character grouping or defines a back reference.
$	Matches the end of the line.
^	Matches the beginning of the line.
^	Matches any character except for the newline
	Quotes the next meta-character.
w	Matches any string containing solely underscore and alphanumeric characters. This is the same as [a-zA-Z0-9_]
W	Matches a string, omitting the underscore and alphanumeric characters.
.	Matches any string except some special symbol and white space character.

Quantifiers	Description
+	Matches at least one character.
*	Matches zero or more characters.
?	Matches only zero or one character
{m}	Matches exactly m number of characters.
{m,}	Matches ranging from m to unlimited number of characters.
{m,n}	Matches ranging m to n number of characters.

Modifiers	Description
I	Perform a case-insensitive search.
G	Find all occurrences (perform a global search).
M	Treat a string as (m for multiple) several lines.
S	Treat a string as a single line, ignoring any newline characters found within; this accomplishes just the opposite of the m modifier.
X	Ignore white space and comments within the regular expression.
U	Stop at the first match. Matches the pattern as many times as possible rather than just stop at the first match.

Predefined Character Ranges	Description
[:alpha:]	Lowercase and uppercase alphabetical characters. This can also be specified as [A-Za-z].
[:alnum:]	Lowercase and uppercase alphabetical characters and numberical digits. This can also be specified as [A-Za-z0-9].
[:cntrl:]	Control characters such as tab,escape, or backspace.
[:digit:]	Numerical digits 0 through 9. This can also be specified as [0-9].
[:graph:]	Printable characters found in the range of ASCII 33 to 126.
[:lower:]	Lowercase alphabetical characters. This can also be specified as [a-z].
[:punct:]	Punctuation characters, including ~ ` ! @ # $ % & * ( ) - _ + = { } [ ] : ; ' < > , . ? and /.
[:upper:]	Uppercase alphabetical characters. This can also be specified as [a-z].
[:space:]	White-space characters, including the space, horizontal tab, vertical tab, new line, form feed, aor carriage return.
[:xdigit:]	Hexadecimal characters, This can also be specified as [a-fA-F0-9].

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Regular Expression Cheat Sheet

Some of useful regular expression

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