[SOLVED] String Positions

[thiggins09]

What would be the best way to get the closest occurrence of a given string before a given position?

 

For example

 

$x='aaCaBaaaCaaaBaB'

 

If you wanted to find the position of the closest C, before the second to last B, (position 12), how would you go about doing that?

[GingerRobot]

I'd reverse the string, find the first occurence after the given offset, then work out the position in the unreversed string:

 

<?php
$str = 'aaCaBaaaCaaaBaB';
$char = 'C';
$start = 12;//the position of second to last B
$start_rev = strlen($str) - 1 - $start;//position of character in reversed string
$str_rev = strrev($str);
$pos = strpos($str_rev,$char,$start_rev);
$original_pos = strlen($str) - 1 - $pos;//the position of the character in the original string.
echo 'The first occurence of '.$char.' before the character at position '.$start. ' is at postion '. $original_pos;
?>

[thiggins09]

Thanks!