Key Parameter Issues

Question

I just started learning PHP, and I have some questions about parameters. Consider DateTime class PHP DateTime Class Manual

public __construct ([ string $time = "now" [, DateTimeZone $timezone = NULL ]] )
public DateTime setDate ( int $year , int $month , int $day )

Here is my question:

Why are the parameters in the constructor in brackets when the parameters are setDatenot in brackets?
Why is there a parenthesis inside the parenthesis?
Why is there a comma before the open bracket [,?

Thanks in advance.

+3

Harry cho Apr 19 '12 at 4:27

2 answers

+4

F21 · Accepted Answer · 2012-04-19T04:32:01+0000

Parameters in brackets are optional. Therefore, if I initialize the DateTime class and do not provide a second parameter, it takes a default value null.
: DateTime, 1, 1 2, . 1, 2.
, 1.