From where I learn advance php

Question

I learn from solo learn now I want to be expert

Answer 1

Only from books and official documentation: php.net, phptherightway.com

Answer 2

You can learn here:-)
https://www.udemy.com/learn-advanced-php-programming/

For reference:-)
http://www.php-rocks.com/advanced.php

Answer 3

read official php documentation which is a good source of all concepts.

Answer 4

I saw an advertisement with a bearded php programmer and realized that I know php

Answer 5

function func($arg) {
$result = 0;
for($i=0; $i<$arg; $i++) {
$result = $result + $i;
}
return $result;
}
echo func(5);

how this become 10