Is 0 necessary in 0777 here in PHP?

Question

mkdir("/path/to/my/dir", 0700);

Is the 0 in 0777 necessary?

Answer 1

Yes. The leading zero will make the number interpreted as octal number; without it would be interpreted as decimal number.

var_dump(0700); // int(448)
var_dump(700);  // int(700)