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Q about substr

Posted on 2008-10-12
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Last Modified: 2012-05-05
hi

$pharse1 is a substring of $text,
how can I get the the 12 cases before phrase1?
(there is only one phrase1 in $text)

regards
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Question by:uk1900
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9 Comments
 
LVL 9

Expert Comment

by:khaledf
ID: 22700229
your question is not clear enough.
can you explain this question by example?
"how can I get the the 12 cases before phrase1?"
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Author Comment

by:uk1900
ID: 22700386
lets say
$text =  "abcdefghijklmnopqrstuvqxyz";
$phrase1 = "mnopq";

how can I get the 12 letter before "mnopq" in $text;
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LVL 27

Accepted Solution

by:
ddrudik earned 1600 total points
ID: 22700392
For the 12 letters prior:
<?php
$phrase1="test";
$text="43210987654321test123456";
echo substr($text,strpos($text,$phrase1)-12,12);
?>

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LVL 27

Expert Comment

by:ddrudik
ID: 22700403
String functions would be preferred over regex functions, but here's another one of the ways to match these 12 characters:
<?php
$phrase1="test";
$text="43210987654321test123456";
preg_match("/.{12}(?=$phrase1)/",$text,$match);
echo $match[0];
?>

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Author Comment

by:uk1900
ID: 22700549
both works,
which one is has the best speed performence when it comes to 100s of loops?
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LVL 9

Assisted Solution

by:khaledf
khaledf earned 400 total points
ID: 22702829
to check which one is best for performance, put the code between these 2 php blocks

<?  $time = microtime(true);  ?>


// YOUR CODE HERE

<?  
$time2 = microtime(true);  
$gentime = $time2 - $time;
echo "$gentime";
?>

and see which one is faster
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LVL 27

Expert Comment

by:ddrudik
ID: 22703066
uk1900, it would be expected that string functions (substr etc.) are always faster than regex functions, regex functions are best used when string functions are not available for the specific task.  I just thought I would show another way to do it.
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Author Closing Comment

by:uk1900
ID: 31505532
thank you for your help
0
 
LVL 27

Expert Comment

by:ddrudik
ID: 22707697
Thanks for the question and the points.
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