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Want regular expression to stop at first occurrence of word

P: n/a
Hello all,

Say I have the following string:

$string = "list of whales: white beluga whale humpback whale atlantic
humpback whale";

I want to pull out the first kind of whale (white beluga). I want
this to work regardless of whether the first whale is a white beluga,
or a humpback, etc. I tried:

$regExp = "/(whales:)(.*)(whale)/";
$outputArray = array();
if ( preg_match($regExp, $string, $outputArray) ) {
print "$outputArray[2]<br>";
}

But, the output is "white beluga whale humpback whale atlantic
humpback", as I expected. I know how to stop after finding a single
character, but I can't figure out how to stop after finding a single
instance of a word. Any help? Thanks.

Feb 26 '07 #1
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2 Replies


P: n/a
e_*******@hotmail.com wrote:
$string = "list of whales: white beluga whale humpback whale atlantic
humpback whale";
$regExp = "/(whales:)(.*)(whale)/";
if ( preg_match($regExp, $string, $outputArray) ) {
But, the output is "white beluga whale humpback whale atlantic
humpback", as I expected. I know how to stop after finding a single
character, but I can't figure out how to stop after finding a single
instance of a word. Any help? Thanks.
RegEx are greedy. That means RegEx match as much as they can. This means
your Expression stops with the last whale. To make it stop with the
first whale make your Expression ungreedey:
$regExp = "/(whales:)(.*?)(whale)/";

or

$regExp = "/(whales:)(.*)(whale)/U";

see:
http://en.wikipedia.org/wiki/Regular...dy_expressions

Heiko
--
http://portal.richler.de/ Namensportal zu Richler
http://www.richler.de/ Heiko Richler: Computer - Know How!
http://www.richler.info/ private Homepage
Feb 26 '07 #2

P: n/a
On Feb 25, 10:25 pm, Heiko Richler <heiko-rich...@nefkom.netwrote:
e_matt...@hotmail.com wrote:
$string = "list of whales: white beluga whale humpback whale atlantic
humpback whale";
$regExp = "/(whales:)(.*)(whale)/";
if ( preg_match($regExp, $string, $outputArray) ) {
But, the output is "white beluga whale humpback whale atlantic
humpback", as I expected. I know how to stop after finding a single
character, but I can't figure out how to stop after finding a single
instance of a word. Any help? Thanks.

RegEx are greedy. That means RegEx match as much as they can. This means
your Expression stops with the last whale. To make it stop with the
first whale make your Expression ungreedey:

$regExp = "/(whales:)(.*?)(whale)/";

or

$regExp = "/(whales:)(.*)(whale)/U";

see:http://en.wikipedia.org/wiki/Regular...dy_expressions

Heiko
--http://portal.richler.de/Namensportal zu Richlerhttp://www.richler.de/ Heiko Richler: Computer - Know How!http://www.richler.info/ private Homepage
Thank you very much, both for the answer and the reference.

Eric

Feb 26 '07 #3

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