strcspn(string,char,start,length);

<?php
// count all character with whitespace
str="Hello Javatpoint";
echo "Your string is: ".str;
echo "<br>";
echo "By using strcspn() function:".strcspn($str,"w");
?>

Your string is: Hello Javatpoint
By using strcspn() function:16

<?php
//The start position is 0 and the length of the search string is 5.
str="Hello Javatpoint";
echo "Your string is: ".str;
echo "<br>";
echo "By using strcspn() function:".strcspn($str,"w","0","5");
?>

Your string is: Hello Javatpoint
By using strcspn() function:5

<?php
a = strcspn('abcd',  'apple');
var_dump(a);
?>

int(0)

<?php
str = strcspn('abcd',  'banana');
var_dump(str);
?>

int(0)

<?php
str = strcspn('hello', 'l');
var_dump(str);
?>

int(2)

<?php
str = strcspn('hello', 'world');
var_dump(str);
?>

int(2)

<?php
str = strcspn('abcdhelloabcd', 'abcd', -9);
var_dump(str);
?>

int(5)

<?php
str = strcspn('abcdhelloabcd', 'abcd', -9, -5);
var_dump(str);
?>

int(4)