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Top Forums Shell Programming and Scripting Regex issue with \s in character class. Post 303042656 by Scrutinizer on Thursday 2nd of January 2020 08:56:49 AM
Old 01-02-2020
Quote:
Originally Posted by Neo
Also, another FWIW:

Code:
linux# php -a
Interactive mode enabled

php > $a = ' FOO ';
php > echo preg_match('/[\s][A-Z]+[\s]/', $a,$matches);
1
php > echo $matches[0];
 FOO 
php >

so, it works in a PHP REGEX .....
POSIX regular expressions (BRE/ERE) and the GNU and BSD derivatives are the exception, rather than the norm, in that \ is not special/meta within a character class (bracket) expression.

In (I think all) other regex flavours \ is special in a character class (bracket) expression.


--
Shortcuts like \s are not part of POSIX BRE/ERE, but are supported as an extension in BSD and GNU implementations.

Last edited by Scrutinizer; 01-02-2020 at 10:04 AM..
 

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EREG_REPLACE(3) 							 1							   EREG_REPLACE(3)

ereg_replace - Replace regular expression

SYNOPSIS
string ereg_replace (string $pattern, string $replacement, string $string) DESCRIPTION
This function scans $string for matches to $pattern, then replaces the matched text with $replacement. Warning This function has been DEPRECATED as of PHP 5.3.0. Relying on this feature is highly discouraged. PARAMETERS
o $pattern - A POSIX extended regular expression. o $replacement - If $pattern contains parenthesized substrings, $replacement may contain substrings of the form digit, which will be replaced by the text matching the digit'th parenthesized substring; will produce the entire contents of string. Up to nine substrings may be used. Parentheses may be nested, in which case they are counted by the opening parenthesis. o $string - The input string. RETURN VALUES
The modified string is returned. If no matches are found in $string, then it will be returned unchanged. EXAMPLES
For example, the following code snippet prints "This was a test" three times: Example #1 ereg_replace(3) example <?php $string = "This is a test"; echo str_replace(" is", " was", $string); echo ereg_replace("( )is", "\1was", $string); echo ereg_replace("(( )is)", "\2was", $string); ?> One thing to take note of is that if you use an integer value as the $replacement parameter, you may not get the results you expect. This is because ereg_replace(3) will interpret the number as the ordinal value of a character, and apply that. For instance: Example #2 ereg_replace(3) example <?php /* This will not work as expected. */ $num = 4; $string = "This string has four words."; $string = ereg_replace('four', $num, $string); echo $string; /* Output: 'This string has words.' */ /* This will work. */ $num = '4'; $string = "This string has four words."; $string = ereg_replace('four', $num, $string); echo $string; /* Output: 'This string has 4 words.' */ ?> Example #3 Replace URLs with links <?php $text = ereg_replace("[[:alpha:]]+://[^<>[:space:]]+[[:alnum:]/]", '<a href="\0">\0</a>', $text); ?> NOTES
Note As of PHP 5.3.0, the regex extension is deprecated in favor of the PCRE extension. Calling this function will issue an E_DEPRECATED notice. See the list of differences for help on converting to PCRE. Tip ereg_replace(3) is deprecated as of PHP 5.3.0. preg_replace(3) is the suggested alternative to this function. SEE ALSO
ereg(3), eregi(3), eregi_replace(3), str_replace(3), preg_replace(3), quotemeta(3). PHP Documentation Group EREG_REPLACE(3)
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