strrpos
This function is significantly faster for checking illegal characters than the equivalent preg_match() method.
strspn
(PHP 4, PHP 5)
strspn — Encuentra la longitud del segmento inicial de un string que consista únicamente en caracteres contenidos dentro de una máscara dada.
Descripción
int strspn
( string
$subject
, string $mask
[, int $start
[, int $length
]] )
Encuentra la longitud del segmento inicial de subject
que contiene solamente caracteres de mask.
Si start y length
son omitidos, entonces la totalidad de subject será
examinada. Si son incluidos, entonces el efecto será el mismo que
llamando strspn(substr($subject, $start, $length),
$mask) (ver substr
para más información).
La línea de código:
<?php
$var = strspn("42 is the answer to the 128th question.", "1234567890");
?>
subject que consiste solamente en caracteres
contenidos dentro de "1234567890".
Parámetros
-
subject -
El string a examinar.
-
mask -
La lista de caracteres permitidos.
-
start -
La posición en
subjectdonde iniciar la búsqueda.Si
startes dado y no es negativo, entonces strspn() comenzará a examinar asubjecten la posiciónstartésima. Por ejemplo, en el string 'abcdef', el caracter en la posición 0 es 'a', el caracter en la posición 2 es 'c' y así sucesivamente.Si
startes dado y es negativo, entonces strspn() comenzará a examinarsubjectdesde lastartésima posición desde el final desubject. -
length -
La longitud del segmento de
subjecta examinar.Si
lengthes dado y no es negativo, entoncessubjectserá examinado por el númerolengthde caracteres después de la posición de inicio.Si
lengthes dado y es negativo, entoncessubjectsera examinado desde la posición de inicio hasta el númerolengthde caracteres desde el final desubject.
Valores devueltos
Devuelve la longitud del segmento inicial de subject
el cual enteramente consiste en caracteres en mask.
Historial de cambios
| Versión | Descripción |
|---|---|
| 4.3.0 |
Fueron agregados los parámetros start
y length
|
Ejemplos
Ejemplo #1 Ejemplo de strspn()
<?php
// subject no inicia con ningún caracter de mask
var_dump(strspn("foo", "o"));
// examina dos caracteres de subject iniciando en el offset 1
var_dump(strspn("foo", "o", 1, 2));
// examina un caracter de subject iniciando en el offset 1
var_dump(strspn("foo", "o", 1, 1));
?>
El resultado del ejemplo sería:
int(0) int(2) int(1)
Notas
Nota: Esta función es segura binariamente.
add a note
User Contributed Notes
strspn - [6 notes]
B Crawford ¶
5 years ago
barry dot balkowski at gmail dot com ¶
4 years ago
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
bob at example dot com ¶
1 year ago
Quick way to check if a string consists entirely of characters within the mask is to compare strspn with strlen eg:
<?php
$path = $_SERVER['PATH_INFO'];
if (strspn($path,'/') == strlen($path)) {
//PATH_INFO is empty
}
?>
mrsohailkhan at gmail dot com ¶
2 years ago
very dificult to get from the definition directly, while i search for that,i came to know that
strspn() will tell you the length of a string consisting entirely of the set of characters in accept set. That is, it starts walking down str until it finds a character that is not in the set (that is, a character that is not to be accepted), and returns the length of the string so far.
and
strcspn() works much the same way, except that it walks down str until it finds a character in the reject set (that is, a character that is to be rejected.) It then returns the length of the string so far.
<?php
$acceptSet = "aeiou";
$rejectSet = "y";
$str1 ="a banana";
$str2 ="the bolivian navy on manuvers in the south pacific";
echo $n = strspn($str1,$acceptSet);// $n == 1, just "a"
echo $n = strcspn($str2,$rejectSet);// n = 16, "the bolivian nav"
?>
hope this example will help in understanding the concept of strspn() and strcspn().
AT-HE (at_he.hotmail) ¶
2 years ago
you can use this function with strlen to check illegal characters, string lenght must be the same than strspn (characters from my string contained in another)
<?php
$digits='0123456789';
if (strlen($phone) != strspn($phone,$digits))
echo "illegal characters";
?>
Dmitry Mazur ¶
4 years ago
The second parameter is a set of allowed characters.
strspn will return an zero-based index of a first non-allowed character.