PHP Unconference Europe 2015

strspn

(PHP 4, PHP 5)

strspnEncontra o comprimento do segmento inicial combinando com a máscara

Descrição

int strspn ( string $str1 , string $str2 [, int $start [, int $length ]] )

Encontra o comprimento do segmento inicial combinando com a máscara.

A linha do código:

<?php
$var 
strspn("42 is the answer, what is the question ...""1234567890");
?>
atribuirá 2 para $var, porque a string "42" será o maior segmento contendo caracteres de "1234567890".

Parâmetros

str1

A primeira string.

str2

A segunda string.

start

A posição inicial da string para examinar. Valor negativo conta posição do final da string.

length

O tamanho da string para examinar. Valor negativo define tamanho do final de uma string.

Valor Retornado

Retorna o comprimento do segmento inicial de str1 que consiste inteiramente dos caracteres em str2.

Changelog

Versão Descrição
4.3.0 Os parâmetros start e length foram adicionados

Exemplos

Exemplo #1 Exemplo da strspn()

<?php
echo strspn("foo""o"12); // 2
?>

Notas

Nota: Esta função é binary-safe.

Veja Também

  • strcspn() - Encontra o tamanho do segmento inicial que não contenha a máscara

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User Contributed Notes 6 notes

up
3
B Crawford
7 years ago
This function is significantly faster for checking illegal characters than the equivalent preg_match() method.
up
2
barry dot balkowski at gmail dot com
6 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
up
1
AT-HE (at_he.hotmail)
3 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";

?>
up
1
Dmitry Mazur
5 years ago
The second parameter is a set of allowed characters.
strspn will return an zero-based index of a first non-allowed character.
up
1
mrsohailkhan at gmail dot com
3 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().
up
-1
bob at example dot com
2 years 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
}
?>
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