strrpos
It took me some time to understand the way this function works…
I’ve compiled my own explanation with my own words that is more understandable for me personally than the official one or those that can be found in different tutorials on the web.
Perhaps, it will save someone several minutes…
<?php
strspn(string $haystack, string $char_list [, int $start [, int $length]])
?>
The way it works:
- searches for a segment of $haystack that consists entirely from supplied through the second argument chars
- $haystack must start from one of the chars supplied through $char_list, otherwise the function will find nothing
- as soon as the function encounters a char that was not mentioned in $chars it understands that the segment is over and stops (it doesn’t search for the second, third and so on segments)
- finally, it measures the segment’s length and return it (i.e. length)
In other words it finds a span (only the first one) in the string that consists entirely form chars supplied in $chars_list and returns its length
strspn
(PHP 4, PHP 5)
strspn — Encuentra la longitud del primer segmento de una cadena que coincide con la máscara
Descripción
int strspn
( string $cadena1
, string $cadena2
[, int $comienzo
[, int $final
]] )
Devuelve la longitud del primer segmento de cadena1 que coincide completamente con todos los caracteres contenidos en cadena2 .
En el siguiente ejemplo:
<?php
$var = strspn("42 es la respuesta, cual es la pregunta ...", "1234567890");
?>
Desde la versión de PHP 4.3.0, strspn() acepta 2 parámetros opcionales de tipo integer y que se pueden emplear para indicar la posición de comienzo y final de la cadena que se va a examinar.
<?php
echo strspn('zoologìa', 'o', 1, 4); // La salida es: 2
?>
Note: Esta función es segura binariamente.
Vea también strcspn().
add a note
User Contributed Notesstrspn
barry dot balkowski at gmail dot com
08-Aug-2008 11:12
08-Aug-2008 11:12
B Crawford
03-Oct-2007 02:20
03-Oct-2007 02:20
This function is significantly faster for checking illegal characters than the equivalent preg_match() method.