strspn
(PHP 4, PHP 5, PHP 7, PHP 8)
strspn — Finds the length of the initial segment of a string consisting entirely of characters contained within a given mask
Description
string
$string,string
$characters,int
$offset = 0,?int
$length = null): int
Finds the length of the initial segment of string
that contains only characters from characters.
If offset and length
are omitted, then all of string will be
examined. If they are included, then the effect will be the same as
calling strspn(substr($string, $offset, $length),
$characters) (see substr
for more information).
The line of code:
<?php
$var = strspn("42 is the answer to the 128th question.", "1234567890");
?>
2 to $var,
because the string "42" is the initial segment
of string that consists only of characters
contained within "1234567890".
Parameters
-
string -
The string to examine.
-
characters -
The list of allowable characters.
-
offset -
The position in
stringto start searching.If
offsetis given and is non-negative, then strspn() will begin examiningstringat theoffset'th position. For instance, in the string 'abcdef', the character at position0is 'a', the character at position2is 'c', and so forth.If
offsetis given and is negative, then strspn() will begin examiningstringat theoffset'th position from the end ofstring. -
length -
The length of the segment from
stringto examine.If
lengthis given and is non-negative, thenstringwill be examined forlengthcharacters after the starting position.If
lengthis given and is negative, thenstringwill be examined from the starting position up tolengthcharacters from the end ofstring.
Return Values
Returns the length of the initial segment of string
which consists entirely of characters in characters.
Note:
When a
offsetparameter is set, the returned length is counted starting from this position, not from the beginning ofstring.
Changelog
| Version | Description |
|---|---|
| 8.0.0 |
length is nullable now.
|
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", 1, 2));
// examine one character from subject starting at offset 1
var_dump(strspn("foo", "o", 1, 1));
?>
The above example will output:
int(0) int(2) int(1)
Notes
Note: This function is binary-safe.
