note 86824 modified in function.mb-split by felipe
| From: | felipe@php.net | Date: | Wed, 05 Nov 2008 13:42:09 +0000 |
| Subject: | note 86824 modified in function.mb-split by felipe | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-146157@lists.php.net to get a copy of this message | ||
The code
<?php
function mbStringToArray ($string) {
$strlen = mb_strlen($string);
while ($strlen) {
$array[] = mb_substr($string,0,1,"UTF-8");
$string = mb_substr($string,1,$strlen,"UTF-8");
$strlen = mb_strlen($string);
}
return $array;
}
?>
may be a bit inefficient cuz this asignment :
<?php $string = mb_substr($string,1,$strlen,"UTF-8"); ?>
in cycle is worth n-i operations, where n - is initial string length and i - the current cycle
number.
Total complexity of the algorithm becomes O(n*n / 2).
I would like propose following algorithm:
<?php
mb_regex_encoding('UTF-8');
mb_internal_encoding('UTF-8' );
$strArray = array();
for ( $i=0; $i < mb_strlen($str); $i++ ) {
$strArray[] = mb_substr($str, $i, 1) ;
}
?>
Now it depends on the complexity of the mb_substr($str, $i, 1).
If it is constant, then the whole algorithm complexity becomes O(n)
--was--
The code
function mbStringToArray ($string) {
$strlen = mb_strlen($string);
while ($strlen) {
$array[] = mb_substr($string,0,1,"UTF-8");
$string = mb_substr($string,1,$strlen,"UTF-8");
$strlen = mb_strlen($string);
}
return $array;
}
may be a bit inefficient cuz this asignment :
$string = mb_substr($string,1,$strlen,"UTF-8");
in cycle is worth n-i operations, where n - is initial string length and i - the current cycle
number.
Total complexity of the algorithm becomes O(n*n / 2).
I would like propose following algorithm:
mb_regex_encoding('UTF-8');
mb_internal_encoding('UTF-8' );
$strArray = array();
for ( $i=0; $i < mb_strlen($str); $i++ ) {
$strArray[] = mb_substr($str, $i, 1) ;
}
Now it depends on the complexity of the mb_substr($str, $i, 1).
If it is constant, then the whole algorithm complexity becomes O(n)
http://php.net/manual/en/function.mb-split.php