How does Casting work in PHP?

Question

What does not work:

(int)08 == (int)09==0

But is that so?

(int)07==7 
(int)06==6 

Answer 1

08 is in octal base (because it starts with 0), so it is not valid. See the documentation .

Answer 2

because 08and 09are not valid octal numbers. see warning in docs .

Answer 3

.

Answer 4

// Syntax error
//(int)08 == (int)09==0

// This works
(int)08==0;
(int)09==0;

// This also works
(int)08 == ((int)09==0);

Answer 5

(int)

intval().

Answer 6

0x.

,

 $num = (int)0x9
 $num == 9