mb_ereg_search_setpos

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

mb_ereg_search_setposSelecciona el punto de partida para la búsqueda mediante expresión regular

Descripción

mb_ereg_search_setpos(int $offset): bool

mb_ereg_search_setpos() selecciona el punto de partida para la búsqueda que va a realizar la función mb_ereg_search().

Parámetros

offset

La posición a definir. Si es negativa, se cuenta desde el final de la cadena.

Valores devueltos

Esta función retorna true en caso de éxito o false si ocurre un error.

Historial de cambios

Versión Descripción
7.1.0 Se ha añadido el soporte para un offset negativo.

Notas

Nota:

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

Ver también

  • mb_regex_encoding() - Define/Recupera la codificación de caracteres para las expresiones regulares multioctetos
  • mb_ereg_search_init() - Configura las cadenas y las expresiones regulares para el soporte de caracteres multioctetos

add a note

User Contributed Notes 1 note

up
-4
phpnet at osps dot net
3 years 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=
?>
To Top