```STRSPN(3)								 1								 STRSPN(3)

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

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

DESCRIPTION
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 call-

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 \$subject that consists only of characters contained within "1234567890".

PARAMETERS
o \$subject
- The string to examine.

- The list of allowable characters.

o \$start
- The position in \$subject to start searching.	If \$start is given and is non-negative, then strspn(3) will begin examining  \$sub-
ject at the \$start'th position. For instance, in the string ' abcdef', the character at position 0 is ' a', the character at posi-
tion 2 is ' c', and so forth.  If \$start is given and is negative, then strspn(3) will begin examining \$subject at  the  \$start'th
position from the end of \$subject.

o \$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 \$length is 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.

EXAMPLES
Example #1

strspn(3) example

<?php
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.