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 — Trova la lunghezza di un testo che corrisponde alla maschera data
Descrizione
int strspn
( string $str1
, string $str2
[, int $start
[, int $length
]] )
Restituisce la lunghezza di un segmento di str1 che contiene completamente i caratteri presenti in str2 .
Il seguente codice:
<?php
$var = strspn("42 is the answer, what is the question ...", "1234567890");
?>
Dal PHP 4.3.0, strspn() accetta altri due parametri interi opzionali: start che può essere usato per indicare la posizione di inizio da cui cercare, e length per indicare la lunghezza della stringa da esaminare.
<?php
echo strspn("foo", "o", 1, 2); // 2
?>
Nota: Questa funzione è binary-safe (gestisce correttamente i file binari)
Vedere anche 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.