What is the PHP best practice for using functions that return true or false?

Question

After playing with PHP, I discovered that true is returned as 1 and false as null.

echo (5 == 5) // displays 1
echo (5 == 4) // displays nothing

Answer 1

1. Sure. Unless you need it in a different sort of structure, e.g. a while loop.

2. You never would. Always invert the normal function directly.

3. When you need to differentiate false from 0, '', etc.