strspn
Finds the length of the initial segment of a string consisting
entirely of characters contained within a given mask
Description
int strspn(
string $string
,
string $characters
,
int $offset
= 0,
intnull $length
= null
)
If offset
and length
are omitted, then all of string
will be
examined. If they are included, then the effect will be the same as
calling strspn(substr($string, $offset, $length),
$characters)
(see substr
for more information).
The line of code:
will assign
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 string
to
start searching.
If offset
is given and is non-negative,
then strspn will begin
examining string
at
the offset
'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 offset
is given and is negative,
then strspn will begin
examining string
at
the offset
'th position from the end
of string
.
-
length
-
The length of the segment from string
to examine.
If length
is given and is non-negative,
then string
will be examined
for length
characters after the starting
position.
If length
is given and is negative,
then string
will be examined from the
starting position up to length
characters from the end of string
.
Return Values
Returns the length of the initial segment of string
which consists entirely of characters in characters
.
Note:
When a offset
parameter is set, the returned length
is counted starting from this position, not from the beginning of
string
.
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:
Notes
Note: This function is
binary-safe.