The first blog post: Why are the optional parameters in the PHP function prototype written this way?

The first article is the beginning. Simply write something.

I just started learning PHP and encountered a problem when reading the PHP Manual: In the function prototype containing optional parameters, the optional parameters are not written in a way that I can understand.

For example, the explode function

<span>array explode ( string $delimiter , string $string [, int $limit ] )
</span>

optional parameters are enclosed in "[square brackets]", then the third parameter $limit is an optional parameter.

But why not write it like this:

<span>array explode ( string $delimiter , string $string ,[int $limit ] )
</span>

I really can’t understand the position of this comma.

The above introduces the first blog post: Why are the optional parameters in the PHP function prototype written like this? , including relevant content, I hope it will be helpful to friends who are interested in PHP tutorials.