How to do an if statement on a function in PHP?

Question

I just realized that you can't just use an if statement on a function, for example this doesn't work:

function sayHello()
{
    echo "Hello World";
}

if(sayHello())
    echo "Function Worked";
else
    echo "Function Failed";

I also saw that a function can't be put as the value of a variable. So how can I do an if statement to check if a function has executed properly and display it to the browser?

Answer 1

It's not working since sayHello() doesn't return anything place return true in there or something.

Answer 2

if (sayHello() === FALSE)
    echo "Function Failed";
else
    echo "Function Worked";

Answer 3

http://www.w3schools.com/php/php_exception.asp