Why do strtotime(' ') and strtotime('.') return a timestamp?

Question

After some messing around with strtotime() in PHP I noticed that it gives a valid timestamp back when you pass in spaces and or dots.

var_dump(strtotime(" "));
var_dump(strtotime("."));
var_dump(strtotime(". .. .. .. .... .. . .. ."));

produces:

int 1443009652
int 1443009652
int 1443009652

Why does PHP see this as valid?

Answer 1

The simplest answer is some of them are falsey

var_dump(DateTime(false)); // date shown is current time

My bet is that the parser (which is trying to clean up a wide variety of acceptable inputs) strips the periods out (that are not being used as a delimiter), leaving only an empty string. It's the only explanation that makes sense.

echo strtotime('1.1.2000'); // outputs 946681200