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Full Discussion: Question on regex with * and .
Top Forums Shell Programming and Scripting Question on regex with * and . Post 302437907 by Franklin52 on Friday 16th of July 2010 02:13:01 PM
Old 07-16-2010
Quote:
Originally Posted by mirage
I have a basic question regarding * and . while using regex:

# echo 3 | grep ^[0123456789]*$
3

I think I understood why it outputs "3" here (because '*' matches zero or more of the previous character) but I don't understand the output of the following command:

# echo 3 | grep ^[0123456789].$
#

I thought I would see "3" here as well since '.' matches "one or more of previous characters". no?
Yes, but after the first character there is no more character to match.
Code:
^[0123456789].$

means 1 character begins with one of the characters between the square brackets and one single character at the end of the line.
This User Gave Thanks to Franklin52 For This Post:
mirage
 

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LEARN ABOUT PHP

mb_regex_set_options

MB_REGEX_SET_OPTIONS(3) 						 1						   MB_REGEX_SET_OPTIONS(3)

mb_regex_set_options - Set/Get the default options for mbregex functions

SYNOPSIS

       string mb_regex_set_options ([string  $options = mb_regex_set_options()])

DESCRIPTION

	Sets the default options described by $options for multibyte regex functions.

PARAMETERS

	      o $options
		-  The	options to set. This is a string where each character is an option. To set a mode, the mode character must be the last one
		set, however there can only be set one mode but multiple options.

	      Regex options

	      +-------+-------------------------------+---+---+
	      |Option | 			      |   |   |
	      |       | 			      |   |   |
	      |       | 	   Meaning	      |   |   |
	      |       | 			      |   |   |
	      +-------+-------------------------------+---+---+
	      |  i    | 			      |   |   |
	      |       | 			      |   |   |
	      |       |      Ambiguity match on       |   |   |
	      |       | 			      |   |   |
	      |  x    | 			      |   |   |
	      |       | 			      |   |   |
	      |       | Enables extended pattern form |   |   |
	      |       | 			      |   |   |
	      |  m    | 			      |   |   |
	      |       | 			      |   |   |
	      |       | 			      |   |   |
	      |       |   '.' matches with newlines   |   |   |
	      |       | 			      |   |   |
	      |  s    | 			      |   |   |
	      |       | 			      |   |   |
	      |       | 			      |   |   |
	      |       |   '^' -> 'A', '$' -> ''    |   |   |
	      |       | 			      |   |   |
	      |  p    | 			      |   |   |
	      |       | 			      |   |   |
	      |       | Same as  both  the  m  and  s |   |   |
	      |       | options 		      |   |   |
	      |       | 			      |   |   |
	      |  l    | 			      |   |   |
	      |       | 			      |   |   |
	      |       |     Finds longest matches     |   |   |
	      |       | 			      |   |   |
	      |  n    | 			      |   |   |
	      |       | 			      |   |   |
	      |       |     Ignores empty matches     |   |   |
	      |       | 			      |   |   |
	      |  e    | 			      |   |   |
	      |       | 			      |   |   |
	      |       |    eval(3) resulting code     |   |   |
	      |       | 			      |   |   |
	      +-------+-------------------------------+---+---+
	      Regex syntax modes

	      +-----+----------------------------+---+---+
	      |Mode |				 |   |	 |
	      |     |				 |   |	 |
	      |     |	       Meaning		 |   |	 |
	      |     |				 |   |	 |
	      +-----+----------------------------+---+---+
	      | j   |				 |   |	 |
	      |     |				 |   |	 |
	      |     | Java (Sun java.util.regex) |   |	 |
	      |     |				 |   |	 |
	      | u   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |	      GNU regex 	 |   |	 |
	      |     |				 |   |	 |
	      | g   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |		 grep		 |   |	 |
	      |     |				 |   |	 |
	      | c   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |		Emacs		 |   |	 |
	      |     |				 |   |	 |
	      | r   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |		 Ruby		 |   |	 |
	      |     |				 |   |	 |
	      | z   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |		 Perl		 |   |	 |
	      |     |				 |   |	 |
	      | b   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |	  POSIX Basic regex	 |   |	 |
	      |     |				 |   |	 |
	      | d   |				 |   |	 |
	      |     |				 |   |	 |
	      |     |	 POSIX Extended regex	 |   |	 |
	      |     |				 |   |	 |
	      +-----+----------------------------+---+---+
RETURN VALUES

	The previous options. If $options is omitted, it returns the string that describes the current options.

SEE ALSO

       mb_split(3), mb_ereg(3), mb_eregi(3).

PHP Documentation Group 												   MB_REGEX_SET_OPTIONS(3)
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