php函数strcspn（）中的“start”参数是做什么的

Question

i was trying to execute the following code

$string ='mynameisjenson';
echo strcspn( $string,'j',11);

the ouput am getting is 3 but really don't know how is gets 3.could any one please explain this

Answer 1

The start parameter tells strcspn() to start looking at that position in the string, instead of starting at the beginning of the string.

strcspn($string, 'j', 11)

is equivalent to

strcspn(substr($string, 11), 'j')

Position 11 in your string is the s character, so it's doing:

strcspn('son', 'j');

Since there's no j in that part of the string, it returns 3.