why (!null) is true?

Question

if(!null)
echo "true";
else
echo "false";

//output : true

Answer 1

Default boolean value of null is false and ! converts it to true

Answer 2

Think of ! as "is not", it helps (that's how CoffeeScript works too, and I love it). So, this:

if(!null)

Means:

if is not null

Answer 3

thanks.