strspn

(PHP 4, PHP 5)

strspn Finds the length of the initial segment of a string consisting entirely of characters contained within a given mask.

Description

int strspn ( string $subject , string $mask [, int $start [, int $length ]] )

Finds the length of the initial segment of subject that contains only characters from mask.

If start and length are omitted, then all of subject will be examined. If they are included, then the effect will be the same as calling strspn(substr($subject, $start, $length), $mask) (see substr for more information).

The line of code:

<?php
$var 
strspn("42 is the answer to the 128th question.""1234567890");
?>
will assign 2 to $var, because the string "42" is the initial segment of subject that consists only of characters contained within "1234567890".

Parameters

subject

The string to examine.

mask

The list of allowable characters.

start

The position in subject to start searching.

If start is given and is non-negative, then strspn() will begin examining subject at the start'th position. For instance, in the string 'abcdef', the character at position 0 is 'a', the character at position 2 is 'c', and so forth.

If start is given and is negative, then strspn() will begin examining subject at the start'th position from the end of subject.

length

The length of the segment from subject to examine.

If length is given and is non-negative, then subject will be examined for length characters after the starting position.

If lengthis given and is negative, then subject will be examined from the starting position up to length characters from the end of subject.

Return Values

Returns the length of the initial segment of subject which consists entirely of characters in mask.

Changelog

Version Description
4.3.0 The start and length parameters were added

Examples

Example #1 strspn() example

<?php
// subject does not start with any characters from mask
var_dump(strspn("foo""o"));

// examine two characters from subject starting at offset 1
var_dump(strspn("foo""o"12));

// examine one character from subject starting at offset 1
var_dump(strspn("foo""o"11));
?>

The above example will output:

int(0)
int(2)
int(1)

Notes

Note: This function is binary-safe.

See Also

  • strcspn() - Find length of initial segment not matching mask

Коментарии

Автор:
This function is significantly faster for checking illegal characters than the equivalent preg_match() method.
2007-10-02 20:20:17
http://php5.kiev.ua/manual/ru/function.strspn.html
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 $haystackstring $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
2008-08-08 05:12:43
http://php5.kiev.ua/manual/ru/function.strspn.html
Автор:
The second parameter is a set of allowed characters.
strspn will return an zero-based index of a first non-allowed character.
2009-03-04 12:23:23
http://php5.kiev.ua/manual/ru/function.strspn.html
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";

?>
2010-11-28 16:45:00
http://php5.kiev.ua/manual/ru/function.strspn.html
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().
2011-02-01 14:56:47
http://php5.kiev.ua/manual/ru/function.strspn.html
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
}
?>
2012-06-05 18:37:24
http://php5.kiev.ua/manual/ru/function.strspn.html
strspon and preg_match seem to be equally fast for validating numbers:

<?php

$testValInvalid 
'foobar123^^';
$testValValid '12346';
$allowedChars '1234567890';

$t1 microtime(true);
for (
$i 0$i 1000000$i++) {
   
assert(strspn($testValInvalid$allowedChars) != strlen($testValInvalid));
   
assert(strspn($testValValid$allowedChars) == strlen($testValValid));
}
print 
'Time taken for strspon: ' . (microtime(true) - $t1);
print 
PHP_EOL;

$t1 microtime(true);
for (
$i 0$i 1000000$i++) {
   
assert(preg_match('/^[0-9]+$/'$testValInvalid) === 0);
   
assert(preg_match('/^[0-9]+$/'$testValValid));
}

print 
'Time taken for preg_match: ' . (microtime(true) - $t1);
print 
PHP_EOL;

/**
nino-mcb:hosp_web ninoskopac$ php test.php
Time taken for strspon: 3.24165391922
Time taken for preg_match: 3.1820080280304
nino-mcb:hosp_web ninoskopac$ php test.php
Time taken for strspon: 3.1806418895721
Time taken for preg_match: 3.2244551181793
 */
?>
2018-02-07 08:59:50
http://php5.kiev.ua/manual/ru/function.strspn.html
Get Group match letter

<?php 

$s
'aaabbbcceeffaaeeeaaabbzmmm';

function 
groupby$s ){
    static 
$a = [];
    static 
$i 0;
   
   
$o strspn$s$s[$i], $i);
   
$a$i ] = [  $s[$i] => $o ];
   
$i += $o;
   
    if( 
$i strlen($s) ) {
       
groupby($s);
    }

    return 
$a;
}

print_r(groupby($s));

?>
2020-08-13 16:34:54
http://php5.kiev.ua/manual/ru/function.strspn.html

    Поддержать сайт на родительском проекте КГБ