Matching pattern then*

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November 11th, 2009, 09:32 PM

ryel01

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Matching pattern then*

I want to "replace with a space" all * characters in a string that are immediately following a group a characters which are not solely letters a-zA-Z - but allowing for leading [-] ie. -example*

So the regex would NOT replace * in the following:

Code:

-example*
example*

because it is only preceeded by letters and an optional - character.

But it WOULD replace the * in the following:

Code:

ex2amle*
example2*
2example*
exa-mple*
-examp2le*
-2example*

November 12th, 2009, 09:24 AM

ManiacDan

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You'll have to anchor the expression at the start of the string:
Perl:
s/^(\-?[a-z]+)\*/$1 /i

PHP:
preg_replace("/^(\-?[a-z]+)\*/i", "\\1 ", $theString);

-Dan

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November 12th, 2009, 05:23 PM

ryel01

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Quote:

Originally Posted by ManiacDan

You'll have to anchor the expression at the start of the string:
Perl:
s/^(\-?[a-z]+)\*/$1 /i

PHP:
preg_replace("/^(\-?[a-z]+)\*/i", "\\1 ", $theString);

-Dan

hi dan,

that finds matches in a string starting with that sequence, but how would you change it to find that sequence "anywhere" in the string?

ie. it could be at the start of the string, at the end of the string, or have a space either side.

November 16th, 2009, 08:33 AM

ManiacDan

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Sorry, you want it to replace the * with a " " whenever the * follows a mixed group of letters and numbers? You can't do that with just a regular expression, the closest you can come is:
preg_replace("/([a-z]*[0-9]+\w*)\*+/i", "\\1 ", $theString);

That replaces everything in your example except for exa-mple, because it doesn't fit the rule you've given anyway. Example script:

PHP Code:


		
			
 $strings = array(

"-example*",

"example*",

"ex2amle*",

"example2*",

"2example*",

"exa-mple*",

"-examp2le*",

"-2example*",

"This is a long example, you should see no space here* but a space 3here* and -here2343* but not here*.");

echo "</pre>";

foreach ( $strings as $theString ) { 

    echo preg_replace("/([a-z]*[0-9]+\w*)\*+/i", "\\1 ", $theString) . "<br />\n";

}

Output:

Code:

-example*
example*
ex2amle 
example2 
2example 
exa-mple*
-examp2le 
-2example 
This is a long example, you should see no space here* but a space 3here and -here2343 but not here*.

-Dan

Matching pattern then*

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