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mb_ereg_search_setpos

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

mb_ereg_search_setposSet start point of next regular expression match

Description

mb_ereg_search_setpos(int $offset): bool

mb_ereg_search_setpos() sets the starting point of a match for mb_ereg_search().

Parameters

offset

The position to set. If it is negative, it counts from the end of the string.

Return Values

Returns true on success or false on failure.

Changelog

Version Description
7.1.0 Support for negative offsets has been added.

Notes

Note:

The internal encoding or the character encoding specified by mb_regex_encoding() will be used as the character encoding for this function.

See Also

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User Contributed Notes 1 note

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-1
phpnet at osps dot net
2 months ago
This method, like mb_ereg_search_pos, appears to use byte offsets, not character offsets. This seems counter intuitive for the mb_* methods, which inherently take a "character" view of strings, as opposed to a "byte" based view. Even the mb_strpos method returns a character offset.

The following code reveals this byte-oriented behaviour:

<?php
    $x
= 'abc456789'. "\u{1000}" .'abc4567890';
   
$re = 'ab.';
    echo
'x='. $x .PHP_EOL;
    echo
're='. $re .PHP_EOL;
   
mb_ereg_search_init( $x );
   
mb_internal_encoding( mb_detect_encoding( $x) );
    echo
'mb_strlen='. mb_strlen( $x ) .PHP_EOL;
    echo
'strlen='. strlen( $x ) .PHP_EOL;
    foreach ( array(
0, 9, 10, 11, 12, 13 ) as $o ) {

       
mb_ereg_search_setpos( $o );
        echo
'Offset='. $o
           
.' mb_substr='. mb_substr( $x, $o )
            .
' substr='. substr( $x, $o )
            .
' mb_ereg_search_regs='. print_r( mb_ereg_search_regs( $re ), true  )
            .
PHP_EOL;
    }

?>
With character offsets, we would expect offsets 11 and above to return no search result, whereas what we see is:

<?php

=abc456789ကabc4567890
re
=ab.
mb_strlen=20
strlen
=22
Offset
=0 mb_substr=abc456789ကabc4567890 substr=abc456789ကabc4567890 mb_ereg_search_regs=Array
(
    [
0] => abc
)

Offset=9 mb_substr=ကabc4567890 substr=ကabc4567890 mb_ereg_search_regs=Array
(
    [
0] => abc
)

Offset=10 mb_substr=abc4567890 substr=��abc4567890 mb_ereg_search_regs=Array
(
    [
0] => abc
)

Offset=11 mb_substr=bc4567890 substr=�abc4567890 mb_ereg_search_regs=Array
(
    [
0] => abc
)

Offset=12 mb_substr=c4567890 substr=abc4567890 mb_ereg_search_regs=Array
(
    [
0] => abc
)

Offset=13 mb_substr=4567890 substr=bc4567890 mb_ereg_search_regs=
?>
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