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How to use regex in MFC?

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How to use regex in MFC?
posted Dec 2, 2014 by Ujjwal Jain

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1 Answer

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Supported Regular Expression Syntax

The following tables are copied from MSDN. You can note that the syntax is not exactly the same as in Perl. For example, the grouping operator is {}, while in Perl it is (), and it doesn't have the {n} (match exactly n times) as in the Perl syntax<.

Metacharacter Meaning

.   Matches any single character.
[ ] Indicates a character class. Matches any character inside the brackets (for example, [abc] matches "a", "b", and "c").
^   If this metacharacter occurs at the start of a character class, it negates the character class. A negated character class matches any character except those inside the brackets (for example, [^abc] matches all characters except "a", "b", and "c").
If ^ is at the beginning of the regular expression, it matches the beginning of the input (for example, ^[abc] will only match input that begins with "a", "b", or "c").

-   In a character class, indicates a range of characters (for example, [0-9] matches any of the digits "0" through "9").
?   Indicates that the preceding expression is optional: it matches once or not at all (for example, [0-9][0-9]? matches "2" and "12").
+   Indicates that the preceding expression matches one or more times (for example, [0-9]+ matches "1", "13", "666", and so on).
*   Indicates that the preceding expression matches zero or more times.
??, +?, *?  Non-greedy versions of ?, +, and *. These match as little as possible, unlike the greedy versions which match as much as possible. Example: given the input "<abc><def>", <.*?> matches "<abc>" while <.*> matches "<abc><def>".
( ) Grouping operator. Example: (\d+,)*\d+ matches a list of numbers separated by commas (such as "1" or "1,23,456").
{ } Indicates a match group. The actual text in the input that matches the expression inside the braces can be retrieved through the CAtlREMatchContext object.
\   Escape character: interpret the next character literally (for example, [0-9]+ matches one or more digits, but [0-9]\+ matches a digit followed by a plus character). Also used for abbreviations (such as \a for any alphanumeric character; see table below).
If \ is followed by a number n, it matches the nth match group (starting from 0). Example: <{.*?}>.*?</\0> matches "<head>Contents</head>".

Note that in C++ string literals, two backslashes must be used: "\+", "\a", "<{.*?}>.*?</\0>".

$ At the end of a regular expression, this character matches the end of the input. Example: [0-9]$ matches a digit at the end of the input.
| Alternation operator: separates two expressions, exactly one of which matches (for example, T|the matches "The" or "the").
! Negation operator: the expression following ! does not match the input. Example: a!b matches "a" not followed by "b".
CAtlRegExp can handle abbreviations, such as \d instead of [0-9]. The abbreviations are provided by the character traits class passed in the CharTraits parameter. The predefined character traits classes provide the following abbreviations:

Abbreviation Matches

\a  Any alphanumeric character: ([a-zA-Z0-9])
\b  White space (blank): ([ \\t])
\c  Any alphabetic character: ([a-zA-Z])
\d  Any decimal digit: ([0-9])
\h  Any hexadecimal digit: ([0-9a-fA-F])
\n  Newline: (\r|(\r?\n))
\q  A quoted string: (\"[^\"]*\")|(\'[^\']*\')
\w  A simple word: ([a-zA-Z]+)
\z  An integer: ([0-9]+)
answer Jun 6, 2017 by Manikandan J
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